1/*
2 * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25#include "precompiled.hpp"
26#include "compiler/compileLog.hpp"
27#include "memory/allocation.inline.hpp"
28#include "opto/addnode.hpp"
29#include "opto/callnode.hpp"
30#include "opto/castnode.hpp"
31#include "opto/connode.hpp"
32#include "opto/convertnode.hpp"
33#include "opto/divnode.hpp"
34#include "opto/loopnode.hpp"
35#include "opto/mulnode.hpp"
36#include "opto/movenode.hpp"
37#include "opto/opaquenode.hpp"
38#include "opto/rootnode.hpp"
39#include "opto/runtime.hpp"
40#include "opto/subnode.hpp"
41#include "opto/superword.hpp"
42#include "opto/vectornode.hpp"
43
44//------------------------------is_loop_exit-----------------------------------
45// Given an IfNode, return the loop-exiting projection or NULL if both
46// arms remain in the loop.
47Node *IdealLoopTree::is_loop_exit(Node *iff) const {
48 if (iff->outcnt() != 2) return NULL; // Ignore partially dead tests
49 PhaseIdealLoop *phase = _phase;
50 // Test is an IfNode, has 2 projections. If BOTH are in the loop
51 // we need loop unswitching instead of peeling.
52 if (!is_member(phase->get_loop(iff->raw_out(0))))
53 return iff->raw_out(0);
54 if (!is_member(phase->get_loop(iff->raw_out(1))))
55 return iff->raw_out(1);
56 return NULL;
57}
58
59
60//=============================================================================
61
62
63//------------------------------record_for_igvn----------------------------
64// Put loop body on igvn work list
65void IdealLoopTree::record_for_igvn() {
66 for (uint i = 0; i < _body.size(); i++) {
67 Node *n = _body.at(i);
68 _phase->_igvn._worklist.push(n);
69 }
70 // put body of outer strip mined loop on igvn work list as well
71 if (_head->is_CountedLoop() && _head->as_Loop()->is_strip_mined()) {
72 CountedLoopNode* l = _head->as_CountedLoop();
73 Node* outer_loop = l->outer_loop();
74 assert(outer_loop != NULL, "missing piece of strip mined loop");
75 _phase->_igvn._worklist.push(outer_loop);
76 Node* outer_loop_tail = l->outer_loop_tail();
77 assert(outer_loop_tail != NULL, "missing piece of strip mined loop");
78 _phase->_igvn._worklist.push(outer_loop_tail);
79 Node* outer_loop_end = l->outer_loop_end();
80 assert(outer_loop_end != NULL, "missing piece of strip mined loop");
81 _phase->_igvn._worklist.push(outer_loop_end);
82 Node* outer_safepoint = l->outer_safepoint();
83 assert(outer_safepoint != NULL, "missing piece of strip mined loop");
84 _phase->_igvn._worklist.push(outer_safepoint);
85 Node* cle_out = _head->as_CountedLoop()->loopexit()->proj_out(false);
86 assert(cle_out != NULL, "missing piece of strip mined loop");
87 _phase->_igvn._worklist.push(cle_out);
88 }
89}
90
91//------------------------------compute_exact_trip_count-----------------------
92// Compute loop trip count if possible. Do not recalculate trip count for
93// split loops (pre-main-post) which have their limits and inits behind Opaque node.
94void IdealLoopTree::compute_trip_count(PhaseIdealLoop* phase) {
95 if (!_head->as_Loop()->is_valid_counted_loop()) {
96 return;
97 }
98 CountedLoopNode* cl = _head->as_CountedLoop();
99 // Trip count may become nonexact for iteration split loops since
100 // RCE modifies limits. Note, _trip_count value is not reset since
101 // it is used to limit unrolling of main loop.
102 cl->set_nonexact_trip_count();
103
104 // Loop's test should be part of loop.
105 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
106 return; // Infinite loop
107
108#ifdef ASSERT
109 BoolTest::mask bt = cl->loopexit()->test_trip();
110 assert(bt == BoolTest::lt || bt == BoolTest::gt ||
111 bt == BoolTest::ne, "canonical test is expected");
112#endif
113
114 Node* init_n = cl->init_trip();
115 Node* limit_n = cl->limit();
116 if (init_n != NULL && limit_n != NULL) {
117 // Use longs to avoid integer overflow.
118 int stride_con = cl->stride_con();
119 const TypeInt* init_type = phase->_igvn.type(init_n)->is_int();
120 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
121 jlong init_con = (stride_con > 0) ? init_type->_lo : init_type->_hi;
122 jlong limit_con = (stride_con > 0) ? limit_type->_hi : limit_type->_lo;
123 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
124 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
125 if (trip_count > 0 && (julong)trip_count < (julong)max_juint) {
126 if (init_n->is_Con() && limit_n->is_Con()) {
127 // Set exact trip count.
128 cl->set_exact_trip_count((uint)trip_count);
129 } else if (cl->unrolled_count() == 1) {
130 // Set maximum trip count before unrolling.
131 cl->set_trip_count((uint)trip_count);
132 }
133 }
134 }
135}
136
137//------------------------------compute_profile_trip_cnt----------------------------
138// Compute loop trip count from profile data as
139// (backedge_count + loop_exit_count) / loop_exit_count
140
141float IdealLoopTree::compute_profile_trip_cnt_helper(Node* n) {
142 if (n->is_If()) {
143 IfNode *iff = n->as_If();
144 if (iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN) {
145 Node *exit = is_loop_exit(iff);
146 if (exit) {
147 float exit_prob = iff->_prob;
148 if (exit->Opcode() == Op_IfFalse) {
149 exit_prob = 1.0 - exit_prob;
150 }
151 if (exit_prob > PROB_MIN) {
152 float exit_cnt = iff->_fcnt * exit_prob;
153 return exit_cnt;
154 }
155 }
156 }
157 }
158 if (n->is_Jump()) {
159 JumpNode *jmp = n->as_Jump();
160 if (jmp->_fcnt != COUNT_UNKNOWN) {
161 float* probs = jmp->_probs;
162 float exit_prob = 0;
163 PhaseIdealLoop *phase = _phase;
164 for (DUIterator_Fast imax, i = jmp->fast_outs(imax); i < imax; i++) {
165 JumpProjNode* u = jmp->fast_out(i)->as_JumpProj();
166 if (!is_member(_phase->get_loop(u))) {
167 exit_prob += probs[u->_con];
168 }
169 }
170 return exit_prob * jmp->_fcnt;
171 }
172 }
173 return 0;
174}
175
176void IdealLoopTree::compute_profile_trip_cnt(PhaseIdealLoop *phase) {
177 if (!_head->is_Loop()) {
178 return;
179 }
180 LoopNode* head = _head->as_Loop();
181 if (head->profile_trip_cnt() != COUNT_UNKNOWN) {
182 return; // Already computed
183 }
184 float trip_cnt = (float)max_jint; // default is big
185
186 Node* back = head->in(LoopNode::LoopBackControl);
187 while (back != head) {
188 if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
189 back->in(0) &&
190 back->in(0)->is_If() &&
191 back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN &&
192 back->in(0)->as_If()->_prob != PROB_UNKNOWN &&
193 (back->Opcode() == Op_IfTrue ? 1-back->in(0)->as_If()->_prob : back->in(0)->as_If()->_prob) > PROB_MIN) {
194 break;
195 }
196 back = phase->idom(back);
197 }
198 if (back != head) {
199 assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
200 back->in(0), "if-projection exists");
201 IfNode* back_if = back->in(0)->as_If();
202 float loop_back_cnt = back_if->_fcnt * (back->Opcode() == Op_IfTrue ? back_if->_prob : (1 - back_if->_prob));
203
204 // Now compute a loop exit count
205 float loop_exit_cnt = 0.0f;
206 if (_child == NULL) {
207 for (uint i = 0; i < _body.size(); i++) {
208 Node *n = _body[i];
209 loop_exit_cnt += compute_profile_trip_cnt_helper(n);
210 }
211 } else {
212 ResourceMark rm;
213 Unique_Node_List wq;
214 wq.push(back);
215 for (uint i = 0; i < wq.size(); i++) {
216 Node *n = wq.at(i);
217 assert(n->is_CFG(), "only control nodes");
218 if (n != head) {
219 if (n->is_Region()) {
220 for (uint j = 1; j < n->req(); j++) {
221 wq.push(n->in(j));
222 }
223 } else {
224 loop_exit_cnt += compute_profile_trip_cnt_helper(n);
225 wq.push(n->in(0));
226 }
227 }
228 }
229
230 }
231 if (loop_exit_cnt > 0.0f) {
232 trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt;
233 } else {
234 // No exit count so use
235 trip_cnt = loop_back_cnt;
236 }
237 } else {
238 head->mark_profile_trip_failed();
239 }
240#ifndef PRODUCT
241 if (TraceProfileTripCount) {
242 tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt);
243 }
244#endif
245 head->set_profile_trip_cnt(trip_cnt);
246}
247
248//---------------------is_invariant_addition-----------------------------
249// Return nonzero index of invariant operand for an Add or Sub
250// of (nonconstant) invariant and variant values. Helper for reassociate_invariants.
251int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) {
252 int op = n->Opcode();
253 if (op == Op_AddI || op == Op_SubI) {
254 bool in1_invar = this->is_invariant(n->in(1));
255 bool in2_invar = this->is_invariant(n->in(2));
256 if (in1_invar && !in2_invar) return 1;
257 if (!in1_invar && in2_invar) return 2;
258 }
259 return 0;
260}
261
262//---------------------reassociate_add_sub-----------------------------
263// Reassociate invariant add and subtract expressions:
264//
265// inv1 + (x + inv2) => ( inv1 + inv2) + x
266// (x + inv2) + inv1 => ( inv1 + inv2) + x
267// inv1 + (x - inv2) => ( inv1 - inv2) + x
268// inv1 - (inv2 - x) => ( inv1 - inv2) + x
269// (x + inv2) - inv1 => (-inv1 + inv2) + x
270// (x - inv2) + inv1 => ( inv1 - inv2) + x
271// (x - inv2) - inv1 => (-inv1 - inv2) + x
272// inv1 + (inv2 - x) => ( inv1 + inv2) - x
273// inv1 - (x - inv2) => ( inv1 + inv2) - x
274// (inv2 - x) + inv1 => ( inv1 + inv2) - x
275// (inv2 - x) - inv1 => (-inv1 + inv2) - x
276// inv1 - (x + inv2) => ( inv1 - inv2) - x
277//
278Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) {
279 if ((!n1->is_Add() && !n1->is_Sub()) || n1->outcnt() == 0) return NULL;
280 if (is_invariant(n1)) return NULL;
281 int inv1_idx = is_invariant_addition(n1, phase);
282 if (!inv1_idx) return NULL;
283 // Don't mess with add of constant (igvn moves them to expression tree root.)
284 if (n1->is_Add() && n1->in(2)->is_Con()) return NULL;
285 Node* inv1 = n1->in(inv1_idx);
286 Node* n2 = n1->in(3 - inv1_idx);
287 int inv2_idx = is_invariant_addition(n2, phase);
288 if (!inv2_idx) return NULL;
289
290 if (!phase->may_require_nodes(10, 10)) return NULL;
291
292 Node* x = n2->in(3 - inv2_idx);
293 Node* inv2 = n2->in(inv2_idx);
294
295 bool neg_x = n2->is_Sub() && inv2_idx == 1;
296 bool neg_inv2 = n2->is_Sub() && inv2_idx == 2;
297 bool neg_inv1 = n1->is_Sub() && inv1_idx == 2;
298 if (n1->is_Sub() && inv1_idx == 1) {
299 neg_x = !neg_x;
300 neg_inv2 = !neg_inv2;
301 }
302 Node* inv1_c = phase->get_ctrl(inv1);
303 Node* inv2_c = phase->get_ctrl(inv2);
304 Node* n_inv1;
305 if (neg_inv1) {
306 Node *zero = phase->_igvn.intcon(0);
307 phase->set_ctrl(zero, phase->C->root());
308 n_inv1 = new SubINode(zero, inv1);
309 phase->register_new_node(n_inv1, inv1_c);
310 } else {
311 n_inv1 = inv1;
312 }
313 Node* inv;
314 if (neg_inv2) {
315 inv = new SubINode(n_inv1, inv2);
316 } else {
317 inv = new AddINode(n_inv1, inv2);
318 }
319 phase->register_new_node(inv, phase->get_early_ctrl(inv));
320
321 Node* addx;
322 if (neg_x) {
323 addx = new SubINode(inv, x);
324 } else {
325 addx = new AddINode(x, inv);
326 }
327 phase->register_new_node(addx, phase->get_ctrl(x));
328 phase->_igvn.replace_node(n1, addx);
329 assert(phase->get_loop(phase->get_ctrl(n1)) == this, "");
330 _body.yank(n1);
331 return addx;
332}
333
334//---------------------reassociate_invariants-----------------------------
335// Reassociate invariant expressions:
336void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) {
337 for (int i = _body.size() - 1; i >= 0; i--) {
338 Node *n = _body.at(i);
339 for (int j = 0; j < 5; j++) {
340 Node* nn = reassociate_add_sub(n, phase);
341 if (nn == NULL) break;
342 n = nn; // again
343 }
344 }
345}
346
347//------------------------------policy_peeling---------------------------------
348// Return TRUE if the loop should be peeled, otherwise return FALSE. Peeling
349// is applicable if we can make a loop-invariant test (usually a null-check)
350// execute before we enter the loop. When TRUE, the estimated node budget is
351// also requested.
352bool IdealLoopTree::policy_peeling(PhaseIdealLoop *phase) {
353 uint estimate = estimate_peeling(phase);
354
355 return estimate == 0 ? false : phase->may_require_nodes(estimate);
356}
357
358// Perform actual policy and size estimate for the loop peeling transform, and
359// return the estimated loop size if peeling is applicable, otherwise return
360// zero. No node budget is allocated.
361uint IdealLoopTree::estimate_peeling(PhaseIdealLoop *phase) {
362
363 // If nodes are depleted, some transform has miscalculated its needs.
364 assert(!phase->exceeding_node_budget(), "sanity");
365
366 // Peeling does loop cloning which can result in O(N^2) node construction.
367 if (_body.size() > 255) {
368 return 0; // Suppress too large body size.
369 }
370 // Optimistic estimate that approximates loop body complexity via data and
371 // control flow fan-out (instead of using the more pessimistic: BodySize^2).
372 uint estimate = est_loop_clone_sz(2);
373
374 if (phase->exceeding_node_budget(estimate)) {
375 return 0; // Too large to safely clone.
376 }
377
378 // Check for vectorized loops, any peeling done was already applied.
379 if (_head->is_CountedLoop()) {
380 CountedLoopNode* cl = _head->as_CountedLoop();
381 if (cl->is_unroll_only() || cl->trip_count() == 1) {
382 return 0;
383 }
384 }
385
386 Node* test = tail();
387
388 while (test != _head) { // Scan till run off top of loop
389 if (test->is_If()) { // Test?
390 Node *ctrl = phase->get_ctrl(test->in(1));
391 if (ctrl->is_top()) {
392 return 0; // Found dead test on live IF? No peeling!
393 }
394 // Standard IF only has one input value to check for loop invariance.
395 assert(test->Opcode() == Op_If ||
396 test->Opcode() == Op_CountedLoopEnd ||
397 test->Opcode() == Op_RangeCheck,
398 "Check this code when new subtype is added");
399 // Condition is not a member of this loop?
400 if (!is_member(phase->get_loop(ctrl)) && is_loop_exit(test)) {
401 return estimate; // Found reason to peel!
402 }
403 }
404 // Walk up dominators to loop _head looking for test which is executed on
405 // every path through the loop.
406 test = phase->idom(test);
407 }
408 return 0;
409}
410
411//------------------------------peeled_dom_test_elim---------------------------
412// If we got the effect of peeling, either by actually peeling or by making
413// a pre-loop which must execute at least once, we can remove all
414// loop-invariant dominated tests in the main body.
415void PhaseIdealLoop::peeled_dom_test_elim(IdealLoopTree *loop, Node_List &old_new) {
416 bool progress = true;
417 while (progress) {
418 progress = false; // Reset for next iteration
419 Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail();
420 Node *test = prev->in(0);
421 while (test != loop->_head) { // Scan till run off top of loop
422
423 int p_op = prev->Opcode();
424 if ((p_op == Op_IfFalse || p_op == Op_IfTrue) &&
425 test->is_If() && // Test?
426 !test->in(1)->is_Con() && // And not already obvious?
427 // Condition is not a member of this loop?
428 !loop->is_member(get_loop(get_ctrl(test->in(1))))){
429 // Walk loop body looking for instances of this test
430 for (uint i = 0; i < loop->_body.size(); i++) {
431 Node *n = loop->_body.at(i);
432 if (n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/) {
433 // IfNode was dominated by version in peeled loop body
434 progress = true;
435 dominated_by(old_new[prev->_idx], n);
436 }
437 }
438 }
439 prev = test;
440 test = idom(test);
441 } // End of scan tests in loop
442
443 } // End of while (progress)
444}
445
446//------------------------------do_peeling-------------------------------------
447// Peel the first iteration of the given loop.
448// Step 1: Clone the loop body. The clone becomes the peeled iteration.
449// The pre-loop illegally has 2 control users (old & new loops).
450// Step 2: Make the old-loop fall-in edges point to the peeled iteration.
451// Do this by making the old-loop fall-in edges act as if they came
452// around the loopback from the prior iteration (follow the old-loop
453// backedges) and then map to the new peeled iteration. This leaves
454// the pre-loop with only 1 user (the new peeled iteration), but the
455// peeled-loop backedge has 2 users.
456// Step 3: Cut the backedge on the clone (so its not a loop) and remove the
457// extra backedge user.
458//
459// orig
460//
461// stmt1
462// |
463// v
464// loop predicate
465// |
466// v
467// loop<----+
468// | |
469// stmt2 |
470// | |
471// v |
472// if ^
473// / \ |
474// / \ |
475// v v |
476// false true |
477// / \ |
478// / ----+
479// |
480// v
481// exit
482//
483//
484// after clone loop
485//
486// stmt1
487// |
488// v
489// loop predicate
490// / \
491// clone / \ orig
492// / \
493// / \
494// v v
495// +---->loop clone loop<----+
496// | | | |
497// | stmt2 clone stmt2 |
498// | | | |
499// | v v |
500// ^ if clone If ^
501// | / \ / \ |
502// | / \ / \ |
503// | v v v v |
504// | true false false true |
505// | / \ / \ |
506// +---- \ / ----+
507// \ /
508// 1v v2
509// region
510// |
511// v
512// exit
513//
514//
515// after peel and predicate move
516//
517// stmt1
518// /
519// /
520// clone / orig
521// /
522// / +----------+
523// / | |
524// / loop predicate |
525// / | |
526// v v |
527// TOP-->loop clone loop<----+ |
528// | | | |
529// stmt2 clone stmt2 | |
530// | | | ^
531// v v | |
532// if clone If ^ |
533// / \ / \ | |
534// / \ / \ | |
535// v v v v | |
536// true false false true | |
537// | \ / \ | |
538// | \ / ----+ ^
539// | \ / |
540// | 1v v2 |
541// v region |
542// | | |
543// | v |
544// | exit |
545// | |
546// +--------------->-----------------+
547//
548//
549// final graph
550//
551// stmt1
552// |
553// v
554// stmt2 clone
555// |
556// v
557// if clone
558// / |
559// / |
560// v v
561// false true
562// | |
563// | v
564// | loop predicate
565// | |
566// | v
567// | loop<----+
568// | | |
569// | stmt2 |
570// | | |
571// | v |
572// v if ^
573// | / \ |
574// | / \ |
575// | v v |
576// | false true |
577// | | \ |
578// v v --+
579// region
580// |
581// v
582// exit
583//
584void PhaseIdealLoop::do_peeling(IdealLoopTree *loop, Node_List &old_new) {
585
586 C->set_major_progress();
587 // Peeling a 'main' loop in a pre/main/post situation obfuscates the
588 // 'pre' loop from the main and the 'pre' can no longer have its
589 // iterations adjusted. Therefore, we need to declare this loop as
590 // no longer a 'main' loop; it will need new pre and post loops before
591 // we can do further RCE.
592#ifndef PRODUCT
593 if (TraceLoopOpts) {
594 tty->print("Peel ");
595 loop->dump_head();
596 }
597#endif
598 LoopNode* head = loop->_head->as_Loop();
599 bool counted_loop = head->is_CountedLoop();
600 if (counted_loop) {
601 CountedLoopNode *cl = head->as_CountedLoop();
602 assert(cl->trip_count() > 0, "peeling a fully unrolled loop");
603 cl->set_trip_count(cl->trip_count() - 1);
604 if (cl->is_main_loop()) {
605 cl->set_normal_loop();
606#ifndef PRODUCT
607 if (PrintOpto && VerifyLoopOptimizations) {
608 tty->print("Peeling a 'main' loop; resetting to 'normal' ");
609 loop->dump_head();
610 }
611#endif
612 }
613 }
614 Node* entry = head->in(LoopNode::EntryControl);
615
616 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
617 // The pre-loop illegally has 2 control users (old & new loops).
618 clone_loop(loop, old_new, dom_depth(head->skip_strip_mined()), ControlAroundStripMined);
619
620 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
621 // Do this by making the old-loop fall-in edges act as if they came
622 // around the loopback from the prior iteration (follow the old-loop
623 // backedges) and then map to the new peeled iteration. This leaves
624 // the pre-loop with only 1 user (the new peeled iteration), but the
625 // peeled-loop backedge has 2 users.
626 Node* new_entry = old_new[head->in(LoopNode::LoopBackControl)->_idx];
627 _igvn.hash_delete(head->skip_strip_mined());
628 head->skip_strip_mined()->set_req(LoopNode::EntryControl, new_entry);
629 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
630 Node* old = head->fast_out(j);
631 if (old->in(0) == loop->_head && old->req() == 3 && old->is_Phi()) {
632 Node* new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
633 if (!new_exit_value) // Backedge value is ALSO loop invariant?
634 // Then loop body backedge value remains the same.
635 new_exit_value = old->in(LoopNode::LoopBackControl);
636 _igvn.hash_delete(old);
637 old->set_req(LoopNode::EntryControl, new_exit_value);
638 }
639 }
640
641
642 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
643 // extra backedge user.
644 Node* new_head = old_new[head->_idx];
645 _igvn.hash_delete(new_head);
646 new_head->set_req(LoopNode::LoopBackControl, C->top());
647 for (DUIterator_Fast j2max, j2 = new_head->fast_outs(j2max); j2 < j2max; j2++) {
648 Node* use = new_head->fast_out(j2);
649 if (use->in(0) == new_head && use->req() == 3 && use->is_Phi()) {
650 _igvn.hash_delete(use);
651 use->set_req(LoopNode::LoopBackControl, C->top());
652 }
653 }
654
655 // Step 4: Correct dom-depth info. Set to loop-head depth.
656
657 int dd = dom_depth(head);
658 set_idom(head, head->in(1), dd);
659 for (uint j3 = 0; j3 < loop->_body.size(); j3++) {
660 Node *old = loop->_body.at(j3);
661 Node *nnn = old_new[old->_idx];
662 if (!has_ctrl(nnn)) {
663 set_idom(nnn, idom(nnn), dd-1);
664 }
665 }
666
667 // Now force out all loop-invariant dominating tests. The optimizer
668 // finds some, but we _know_ they are all useless.
669 peeled_dom_test_elim(loop,old_new);
670
671 loop->record_for_igvn();
672}
673
674// The Estimated Loop Unroll Size: UnrollFactor * (106% * BodySize + BC) + CC,
675// where BC and CC are (totally) ad-hoc/magic "body" and "clone" constants,
676// respectively, used to ensure that node usage estimates made are on the safe
677// side, for the most part. This is a simplified version of the loop clone
678// size calculation in est_loop_clone_sz(), defined for unroll factors larger
679// than one (>1), performing an overflow check and returning 'UINT_MAX' in
680// case of an overflow.
681static uint est_loop_unroll_sz(uint factor, uint size) {
682 precond(0 < factor);
683
684 uint const bc = 5;
685 uint const cc = 7;
686 uint const sz = size + (size + 15) / 16;
687 uint estimate = factor * (sz + bc) + cc;
688
689 return (estimate - cc) / factor == sz + bc ? estimate : UINT_MAX;
690}
691
692#define EMPTY_LOOP_SIZE 7 // Number of nodes in an empty loop.
693
694//------------------------------policy_maximally_unroll------------------------
695// Calculate the exact loop trip-count and return TRUE if loop can be fully,
696// i.e. maximally, unrolled, otherwise return FALSE. When TRUE, the estimated
697// node budget is also requested.
698bool IdealLoopTree::policy_maximally_unroll(PhaseIdealLoop *phase) const {
699 CountedLoopNode *cl = _head->as_CountedLoop();
700 assert(cl->is_normal_loop(), "");
701 if (!cl->is_valid_counted_loop()) {
702 return false; // Malformed counted loop
703 }
704 if (!cl->has_exact_trip_count()) {
705 // Trip count is not exact.
706 return false;
707 }
708
709 uint trip_count = cl->trip_count();
710 // Note, max_juint is used to indicate unknown trip count.
711 assert(trip_count > 1, "one iteration loop should be optimized out already");
712 assert(trip_count < max_juint, "exact trip_count should be less than max_uint.");
713
714 // If nodes are depleted, some transform has miscalculated its needs.
715 assert(!phase->exceeding_node_budget(), "sanity");
716
717 // Real policy: if we maximally unroll, does it get too big?
718 // Allow the unrolled mess to get larger than standard loop
719 // size. After all, it will no longer be a loop.
720 uint body_size = _body.size();
721 uint unroll_limit = (uint)LoopUnrollLimit * 4;
722 assert((intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits");
723 if (trip_count > unroll_limit || body_size > unroll_limit) {
724 return false;
725 }
726
727 // Take into account that after unroll conjoined heads and tails will fold,
728 // otherwise policy_unroll() may allow more unrolling than max unrolling.
729 uint new_body_size = est_loop_unroll_sz(trip_count, body_size - EMPTY_LOOP_SIZE);
730
731 if (new_body_size == UINT_MAX) { // Check for bad estimate (overflow).
732 return false;
733 }
734
735 // Fully unroll a loop with few iterations regardless next conditions since
736 // following loop optimizations will split such loop anyway (pre-main-post).
737 if (trip_count <= 3) {
738 return phase->may_require_nodes(new_body_size);
739 }
740
741 if (new_body_size > unroll_limit ||
742 // Unrolling can result in a large amount of node construction
743 phase->exceeding_node_budget(new_body_size)) {
744 return false;
745 }
746
747 // Do not unroll a loop with String intrinsics code.
748 // String intrinsics are large and have loops.
749 for (uint k = 0; k < _body.size(); k++) {
750 Node* n = _body.at(k);
751 switch (n->Opcode()) {
752 case Op_StrComp:
753 case Op_StrEquals:
754 case Op_StrIndexOf:
755 case Op_StrIndexOfChar:
756 case Op_EncodeISOArray:
757 case Op_AryEq:
758 case Op_HasNegatives: {
759 return false;
760 }
761#if INCLUDE_RTM_OPT
762 case Op_FastLock:
763 case Op_FastUnlock: {
764 // Don't unroll RTM locking code because it is large.
765 if (UseRTMLocking) {
766 return false;
767 }
768 }
769#endif
770 } // switch
771 }
772
773 return phase->may_require_nodes(new_body_size);
774}
775
776
777//------------------------------policy_unroll----------------------------------
778// Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll if
779// the loop is a counted loop and the loop body is small enough. When TRUE,
780// the estimated node budget is also requested.
781bool IdealLoopTree::policy_unroll(PhaseIdealLoop *phase) {
782
783 CountedLoopNode *cl = _head->as_CountedLoop();
784 assert(cl->is_normal_loop() || cl->is_main_loop(), "");
785
786 if (!cl->is_valid_counted_loop()) {
787 return false; // Malformed counted loop
788 }
789
790 // If nodes are depleted, some transform has miscalculated its needs.
791 assert(!phase->exceeding_node_budget(), "sanity");
792
793 // Protect against over-unrolling.
794 // After split at least one iteration will be executed in pre-loop.
795 if (cl->trip_count() <= (cl->is_normal_loop() ? 2u : 1u)) {
796 return false;
797 }
798 _local_loop_unroll_limit = LoopUnrollLimit;
799 _local_loop_unroll_factor = 4;
800 int future_unroll_cnt = cl->unrolled_count() * 2;
801 if (!cl->is_vectorized_loop()) {
802 if (future_unroll_cnt > LoopMaxUnroll) return false;
803 } else {
804 // obey user constraints on vector mapped loops with additional unrolling applied
805 int unroll_constraint = (cl->slp_max_unroll()) ? cl->slp_max_unroll() : 1;
806 if ((future_unroll_cnt / unroll_constraint) > LoopMaxUnroll) return false;
807 }
808
809 // Check for initial stride being a small enough constant
810 if (abs(cl->stride_con()) > (1<<2)*future_unroll_cnt) return false;
811
812 // Don't unroll if the next round of unrolling would push us
813 // over the expected trip count of the loop. One is subtracted
814 // from the expected trip count because the pre-loop normally
815 // executes 1 iteration.
816 if (UnrollLimitForProfileCheck > 0 &&
817 cl->profile_trip_cnt() != COUNT_UNKNOWN &&
818 future_unroll_cnt > UnrollLimitForProfileCheck &&
819 (float)future_unroll_cnt > cl->profile_trip_cnt() - 1.0) {
820 return false;
821 }
822
823 // When unroll count is greater than LoopUnrollMin, don't unroll if:
824 // the residual iterations are more than 10% of the trip count
825 // and rounds of "unroll,optimize" are not making significant progress
826 // Progress defined as current size less than 20% larger than previous size.
827 if (UseSuperWord && cl->node_count_before_unroll() > 0 &&
828 future_unroll_cnt > LoopUnrollMin &&
829 (future_unroll_cnt - 1) * (100 / LoopPercentProfileLimit) > cl->profile_trip_cnt() &&
830 1.2 * cl->node_count_before_unroll() < (double)_body.size()) {
831 return false;
832 }
833
834 Node *init_n = cl->init_trip();
835 Node *limit_n = cl->limit();
836 int stride_con = cl->stride_con();
837 if (limit_n == NULL) return false; // We will dereference it below.
838
839 // Non-constant bounds.
840 // Protect against over-unrolling when init or/and limit are not constant
841 // (so that trip_count's init value is maxint) but iv range is known.
842 if (init_n == NULL || !init_n->is_Con() || !limit_n->is_Con()) {
843 Node* phi = cl->phi();
844 if (phi != NULL) {
845 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
846 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
847 int next_stride = stride_con * 2; // stride after this unroll
848 if (next_stride > 0) {
849 if (iv_type->_lo + next_stride <= iv_type->_lo || // overflow
850 iv_type->_lo + next_stride > iv_type->_hi) {
851 return false; // over-unrolling
852 }
853 } else if (next_stride < 0) {
854 if (iv_type->_hi + next_stride >= iv_type->_hi || // overflow
855 iv_type->_hi + next_stride < iv_type->_lo) {
856 return false; // over-unrolling
857 }
858 }
859 }
860 }
861
862 // After unroll limit will be adjusted: new_limit = limit-stride.
863 // Bailout if adjustment overflow.
864 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
865 if ((stride_con > 0 && ((limit_type->_hi - stride_con) >= limit_type->_hi)) ||
866 (stride_con < 0 && ((limit_type->_lo - stride_con) <= limit_type->_lo)))
867 return false; // overflow
868
869 // Adjust body_size to determine if we unroll or not
870 uint body_size = _body.size();
871 // Key test to unroll loop in CRC32 java code
872 int xors_in_loop = 0;
873 // Also count ModL, DivL and MulL which expand mightly
874 for (uint k = 0; k < _body.size(); k++) {
875 Node* n = _body.at(k);
876 switch (n->Opcode()) {
877 case Op_XorI: xors_in_loop++; break; // CRC32 java code
878 case Op_ModL: body_size += 30; break;
879 case Op_DivL: body_size += 30; break;
880 case Op_MulL: body_size += 10; break;
881 case Op_StrComp:
882 case Op_StrEquals:
883 case Op_StrIndexOf:
884 case Op_StrIndexOfChar:
885 case Op_EncodeISOArray:
886 case Op_AryEq:
887 case Op_HasNegatives: {
888 // Do not unroll a loop with String intrinsics code.
889 // String intrinsics are large and have loops.
890 return false;
891 }
892#if INCLUDE_RTM_OPT
893 case Op_FastLock:
894 case Op_FastUnlock: {
895 // Don't unroll RTM locking code because it is large.
896 if (UseRTMLocking) {
897 return false;
898 }
899 }
900#endif
901 } // switch
902 }
903
904 if (UseSuperWord) {
905 if (!cl->is_reduction_loop()) {
906 phase->mark_reductions(this);
907 }
908
909 // Only attempt slp analysis when user controls do not prohibit it
910 if (LoopMaxUnroll > _local_loop_unroll_factor) {
911 // Once policy_slp_analysis succeeds, mark the loop with the
912 // maximal unroll factor so that we minimize analysis passes
913 if (future_unroll_cnt >= _local_loop_unroll_factor) {
914 policy_unroll_slp_analysis(cl, phase, future_unroll_cnt);
915 }
916 }
917 }
918
919 int slp_max_unroll_factor = cl->slp_max_unroll();
920 if ((LoopMaxUnroll < slp_max_unroll_factor) && FLAG_IS_DEFAULT(LoopMaxUnroll) && UseSubwordForMaxVector) {
921 LoopMaxUnroll = slp_max_unroll_factor;
922 }
923
924 uint estimate = est_loop_clone_sz(2);
925
926 if (cl->has_passed_slp()) {
927 if (slp_max_unroll_factor >= future_unroll_cnt) {
928 return phase->may_require_nodes(estimate);
929 }
930 return false; // Loop too big.
931 }
932
933 // Check for being too big
934 if (body_size > (uint)_local_loop_unroll_limit) {
935 if ((cl->is_subword_loop() || xors_in_loop >= 4) && body_size < 4u * LoopUnrollLimit) {
936 return phase->may_require_nodes(estimate);
937 }
938 return false; // Loop too big.
939 }
940
941 if (cl->is_unroll_only()) {
942 if (TraceSuperWordLoopUnrollAnalysis) {
943 tty->print_cr("policy_unroll passed vector loop(vlen=%d, factor=%d)\n",
944 slp_max_unroll_factor, future_unroll_cnt);
945 }
946 }
947
948 // Unroll once! (Each trip will soon do double iterations)
949 return phase->may_require_nodes(estimate);
950}
951
952void IdealLoopTree::policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_cnt) {
953
954 // If nodes are depleted, some transform has miscalculated its needs.
955 assert(!phase->exceeding_node_budget(), "sanity");
956
957 // Enable this functionality target by target as needed
958 if (SuperWordLoopUnrollAnalysis) {
959 if (!cl->was_slp_analyzed()) {
960 SuperWord sw(phase);
961 sw.transform_loop(this, false);
962
963 // If the loop is slp canonical analyze it
964 if (sw.early_return() == false) {
965 sw.unrolling_analysis(_local_loop_unroll_factor);
966 }
967 }
968
969 if (cl->has_passed_slp()) {
970 int slp_max_unroll_factor = cl->slp_max_unroll();
971 if (slp_max_unroll_factor >= future_unroll_cnt) {
972 int new_limit = cl->node_count_before_unroll() * slp_max_unroll_factor;
973 if (new_limit > LoopUnrollLimit) {
974 if (TraceSuperWordLoopUnrollAnalysis) {
975 tty->print_cr("slp analysis unroll=%d, default limit=%d\n", new_limit, _local_loop_unroll_limit);
976 }
977 _local_loop_unroll_limit = new_limit;
978 }
979 }
980 }
981 }
982}
983
984//------------------------------policy_align-----------------------------------
985// Return TRUE or FALSE if the loop should be cache-line aligned. Gather the
986// expression that does the alignment. Note that only one array base can be
987// aligned in a loop (unless the VM guarantees mutual alignment). Note that
988// if we vectorize short memory ops into longer memory ops, we may want to
989// increase alignment.
990bool IdealLoopTree::policy_align(PhaseIdealLoop *phase) const {
991 return false;
992}
993
994//------------------------------policy_range_check-----------------------------
995// Return TRUE or FALSE if the loop should be range-check-eliminated or not.
996// When TRUE, the estimated node budget is also requested.
997//
998// We will actually perform iteration-splitting, a more powerful form of RCE.
999bool IdealLoopTree::policy_range_check(PhaseIdealLoop *phase) const {
1000 if (!RangeCheckElimination) return false;
1001
1002 // If nodes are depleted, some transform has miscalculated its needs.
1003 assert(!phase->exceeding_node_budget(), "sanity");
1004
1005 CountedLoopNode *cl = _head->as_CountedLoop();
1006 // If we unrolled with no intention of doing RCE and we later changed our
1007 // minds, we got no pre-loop. Either we need to make a new pre-loop, or we
1008 // have to disallow RCE.
1009 if (cl->is_main_no_pre_loop()) return false; // Disallowed for now.
1010 Node *trip_counter = cl->phi();
1011
1012 // check for vectorized loops, some opts are no longer needed
1013 if (cl->is_unroll_only()) return false;
1014
1015 // Check loop body for tests of trip-counter plus loop-invariant vs
1016 // loop-invariant.
1017 for (uint i = 0; i < _body.size(); i++) {
1018 Node *iff = _body[i];
1019 if (iff->Opcode() == Op_If ||
1020 iff->Opcode() == Op_RangeCheck) { // Test?
1021
1022 // Comparing trip+off vs limit
1023 Node *bol = iff->in(1);
1024 if (bol->req() != 2) {
1025 continue; // dead constant test
1026 }
1027 if (!bol->is_Bool()) {
1028 assert(bol->Opcode() == Op_Conv2B, "predicate check only");
1029 continue;
1030 }
1031 if (bol->as_Bool()->_test._test == BoolTest::ne) {
1032 continue; // not RC
1033 }
1034 Node *cmp = bol->in(1);
1035 Node *rc_exp = cmp->in(1);
1036 Node *limit = cmp->in(2);
1037
1038 Node *limit_c = phase->get_ctrl(limit);
1039 if (limit_c == phase->C->top()) {
1040 return false; // Found dead test on live IF? No RCE!
1041 }
1042 if (is_member(phase->get_loop(limit_c))) {
1043 // Compare might have operands swapped; commute them
1044 rc_exp = cmp->in(2);
1045 limit = cmp->in(1);
1046 limit_c = phase->get_ctrl(limit);
1047 if (is_member(phase->get_loop(limit_c))) {
1048 continue; // Both inputs are loop varying; cannot RCE
1049 }
1050 }
1051
1052 if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) {
1053 continue;
1054 }
1055 // Found a test like 'trip+off vs limit'. Test is an IfNode, has two (2)
1056 // projections. If BOTH are in the loop we need loop unswitching instead
1057 // of iteration splitting.
1058 if (is_loop_exit(iff)) {
1059 // Found valid reason to split iterations (if there is room).
1060 // NOTE: Usually a gross overestimate.
1061 return phase->may_require_nodes(est_loop_clone_sz(2));
1062 }
1063 } // End of is IF
1064 }
1065
1066 return false;
1067}
1068
1069//------------------------------policy_peel_only-------------------------------
1070// Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful
1071// for unrolling loops with NO array accesses.
1072bool IdealLoopTree::policy_peel_only(PhaseIdealLoop *phase) const {
1073
1074 // If nodes are depleted, some transform has miscalculated its needs.
1075 assert(!phase->exceeding_node_budget(), "sanity");
1076
1077 // check for vectorized loops, any peeling done was already applied
1078 if (_head->is_CountedLoop() && _head->as_CountedLoop()->is_unroll_only()) {
1079 return false;
1080 }
1081
1082 for (uint i = 0; i < _body.size(); i++) {
1083 if (_body[i]->is_Mem()) {
1084 return false;
1085 }
1086 }
1087 // No memory accesses at all!
1088 return true;
1089}
1090
1091//------------------------------clone_up_backedge_goo--------------------------
1092// If Node n lives in the back_ctrl block and cannot float, we clone a private
1093// version of n in preheader_ctrl block and return that, otherwise return n.
1094Node *PhaseIdealLoop::clone_up_backedge_goo(Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones) {
1095 if (get_ctrl(n) != back_ctrl) return n;
1096
1097 // Only visit once
1098 if (visited.test_set(n->_idx)) {
1099 Node *x = clones.find(n->_idx);
1100 return (x != NULL) ? x : n;
1101 }
1102
1103 Node *x = NULL; // If required, a clone of 'n'
1104 // Check for 'n' being pinned in the backedge.
1105 if (n->in(0) && n->in(0) == back_ctrl) {
1106 assert(clones.find(n->_idx) == NULL, "dead loop");
1107 x = n->clone(); // Clone a copy of 'n' to preheader
1108 clones.push(x, n->_idx);
1109 x->set_req(0, preheader_ctrl); // Fix x's control input to preheader
1110 }
1111
1112 // Recursive fixup any other input edges into x.
1113 // If there are no changes we can just return 'n', otherwise
1114 // we need to clone a private copy and change it.
1115 for (uint i = 1; i < n->req(); i++) {
1116 Node *g = clone_up_backedge_goo(back_ctrl, preheader_ctrl, n->in(i), visited, clones);
1117 if (g != n->in(i)) {
1118 if (!x) {
1119 assert(clones.find(n->_idx) == NULL, "dead loop");
1120 x = n->clone();
1121 clones.push(x, n->_idx);
1122 }
1123 x->set_req(i, g);
1124 }
1125 }
1126 if (x) { // x can legally float to pre-header location
1127 register_new_node(x, preheader_ctrl);
1128 return x;
1129 } else { // raise n to cover LCA of uses
1130 set_ctrl(n, find_non_split_ctrl(back_ctrl->in(0)));
1131 }
1132 return n;
1133}
1134
1135Node* PhaseIdealLoop::cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop) {
1136 Node* castii = new CastIINode(incr, TypeInt::INT, true);
1137 castii->set_req(0, ctrl);
1138 register_new_node(castii, ctrl);
1139 for (DUIterator_Fast imax, i = incr->fast_outs(imax); i < imax; i++) {
1140 Node* n = incr->fast_out(i);
1141 if (n->is_Phi() && n->in(0) == loop) {
1142 int nrep = n->replace_edge(incr, castii);
1143 return castii;
1144 }
1145 }
1146 return NULL;
1147}
1148
1149// Make a copy of the skeleton range check predicates before the main
1150// loop and set the initial value of loop as input. After unrolling,
1151// the range of values for the induction variable in the main loop can
1152// fall outside the allowed range of values by the array access (main
1153// loop is never executed). When that happens, range check
1154// CastII/ConvI2L nodes cause some data paths to die. For consistency,
1155// the control paths must die too but the range checks were removed by
1156// predication. The range checks that we add here guarantee that they do.
1157void PhaseIdealLoop::duplicate_predicates_helper(Node* predicate, Node* start, Node* end,
1158 IdealLoopTree* outer_loop, LoopNode* outer_main_head,
1159 uint dd_main_head) {
1160 if (predicate != NULL) {
1161 IfNode* iff = predicate->in(0)->as_If();
1162 ProjNode* uncommon_proj = iff->proj_out(1 - predicate->as_Proj()->_con);
1163 Node* rgn = uncommon_proj->unique_ctrl_out();
1164 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
1165 assert(iff->in(1)->in(1)->Opcode() == Op_Opaque1, "unexpected predicate shape");
1166 predicate = iff->in(0);
1167 Node* current_proj = outer_main_head->in(LoopNode::EntryControl);
1168 Node* prev_proj = current_proj;
1169 while (predicate != NULL && predicate->is_Proj() && predicate->in(0)->is_If()) {
1170 iff = predicate->in(0)->as_If();
1171 uncommon_proj = iff->proj_out(1 - predicate->as_Proj()->_con);
1172 if (uncommon_proj->unique_ctrl_out() != rgn)
1173 break;
1174 if (iff->in(1)->Opcode() == Op_Opaque4) {
1175 assert(skeleton_predicate_has_opaque(iff), "unexpected");
1176 // Clone the predicate twice and initialize one with the initial
1177 // value of the loop induction variable. Leave the other predicate
1178 // to be initialized when increasing the stride during loop unrolling.
1179 prev_proj = clone_skeleton_predicate(iff, start, predicate, uncommon_proj, current_proj, outer_loop, prev_proj);
1180 assert(skeleton_predicate_has_opaque(prev_proj->in(0)->as_If()) == (start->Opcode() == Op_Opaque1), "");
1181 prev_proj = clone_skeleton_predicate(iff, end, predicate, uncommon_proj, current_proj, outer_loop, prev_proj);
1182 assert(skeleton_predicate_has_opaque(prev_proj->in(0)->as_If()) == (end->Opcode() == Op_Opaque1), "");
1183 // Remove the skeleton predicate from the pre-loop
1184 _igvn.replace_input_of(iff, 1, _igvn.intcon(1));
1185 }
1186 predicate = predicate->in(0)->in(0);
1187 }
1188 _igvn.replace_input_of(outer_main_head, LoopNode::EntryControl, prev_proj);
1189 set_idom(outer_main_head, prev_proj, dd_main_head);
1190 }
1191}
1192
1193static bool skeleton_follow_inputs(Node* n, int op) {
1194 return (n->is_Bool() ||
1195 n->is_Cmp() ||
1196 op == Op_AndL ||
1197 op == Op_OrL ||
1198 op == Op_RShiftL ||
1199 op == Op_LShiftL ||
1200 op == Op_AddL ||
1201 op == Op_AddI ||
1202 op == Op_MulL ||
1203 op == Op_MulI ||
1204 op == Op_SubL ||
1205 op == Op_SubI ||
1206 op == Op_ConvI2L);
1207}
1208
1209bool PhaseIdealLoop::skeleton_predicate_has_opaque(IfNode* iff) {
1210 ResourceMark rm;
1211 Unique_Node_List wq;
1212 wq.push(iff->in(1)->in(1));
1213 for (uint i = 0; i < wq.size(); i++) {
1214 Node* n = wq.at(i);
1215 int op = n->Opcode();
1216 if (skeleton_follow_inputs(n, op)) {
1217 for (uint j = 1; j < n->req(); j++) {
1218 Node* m = n->in(j);
1219 if (m != NULL) {
1220 wq.push(m);
1221 }
1222 }
1223 continue;
1224 }
1225 if (op == Op_Opaque1) {
1226 return true;
1227 }
1228 }
1229 return false;
1230}
1231
1232Node* PhaseIdealLoop::clone_skeleton_predicate(Node* iff, Node* value, Node* predicate, Node* uncommon_proj,
1233 Node* current_proj, IdealLoopTree* outer_loop, Node* prev_proj) {
1234 Node_Stack to_clone(2);
1235 to_clone.push(iff->in(1), 1);
1236 uint current = C->unique();
1237 Node* result = NULL;
1238 // Look for the opaque node to replace with the new value
1239 // and clone everything in between. We keep the Opaque4 node
1240 // so the duplicated predicates are eliminated once loop
1241 // opts are over: they are here only to keep the IR graph
1242 // consistent.
1243 do {
1244 Node* n = to_clone.node();
1245 uint i = to_clone.index();
1246 Node* m = n->in(i);
1247 int op = m->Opcode();
1248 if (skeleton_follow_inputs(m, op)) {
1249 to_clone.push(m, 1);
1250 continue;
1251 }
1252 if (op == Op_Opaque1) {
1253 if (n->_idx < current) {
1254 n = n->clone();
1255 }
1256 n->set_req(i, value);
1257 register_new_node(n, current_proj);
1258 to_clone.set_node(n);
1259 }
1260 for (;;) {
1261 Node* cur = to_clone.node();
1262 uint j = to_clone.index();
1263 if (j+1 < cur->req()) {
1264 to_clone.set_index(j+1);
1265 break;
1266 }
1267 to_clone.pop();
1268 if (to_clone.size() == 0) {
1269 result = cur;
1270 break;
1271 }
1272 Node* next = to_clone.node();
1273 j = to_clone.index();
1274 if (next->in(j) != cur) {
1275 assert(cur->_idx >= current || next->in(j)->Opcode() == Op_Opaque1, "new node or Opaque1 being replaced");
1276 if (next->_idx < current) {
1277 next = next->clone();
1278 register_new_node(next, current_proj);
1279 to_clone.set_node(next);
1280 }
1281 next->set_req(j, cur);
1282 }
1283 }
1284 } while (result == NULL);
1285 assert(result->_idx >= current, "new node expected");
1286
1287 Node* proj = predicate->clone();
1288 Node* other_proj = uncommon_proj->clone();
1289 Node* new_iff = iff->clone();
1290 new_iff->set_req(1, result);
1291 proj->set_req(0, new_iff);
1292 other_proj->set_req(0, new_iff);
1293 Node *frame = new ParmNode(C->start(), TypeFunc::FramePtr);
1294 register_new_node(frame, C->start());
1295 // It's impossible for the predicate to fail at runtime. Use an Halt node.
1296 Node* halt = new HaltNode(other_proj, frame);
1297 C->root()->add_req(halt);
1298 new_iff->set_req(0, prev_proj);
1299
1300 register_control(new_iff, outer_loop->_parent, prev_proj);
1301 register_control(proj, outer_loop->_parent, new_iff);
1302 register_control(other_proj, _ltree_root, new_iff);
1303 register_control(halt, _ltree_root, other_proj);
1304 return proj;
1305}
1306
1307void PhaseIdealLoop::duplicate_predicates(CountedLoopNode* pre_head, Node* start, Node* end,
1308 IdealLoopTree* outer_loop, LoopNode* outer_main_head,
1309 uint dd_main_head) {
1310 if (UseLoopPredicate) {
1311 Node* entry = pre_head->in(LoopNode::EntryControl);
1312 Node* predicate = NULL;
1313 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1314 if (predicate != NULL) {
1315 entry = skip_loop_predicates(entry);
1316 }
1317 Node* profile_predicate = NULL;
1318 if (UseProfiledLoopPredicate) {
1319 profile_predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
1320 if (profile_predicate != NULL) {
1321 entry = skip_loop_predicates(entry);
1322 }
1323 }
1324 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1325 duplicate_predicates_helper(predicate, start, end, outer_loop, outer_main_head, dd_main_head);
1326 duplicate_predicates_helper(profile_predicate, start, end, outer_loop, outer_main_head, dd_main_head);
1327 }
1328}
1329
1330//------------------------------insert_pre_post_loops--------------------------
1331// Insert pre and post loops. If peel_only is set, the pre-loop can not have
1332// more iterations added. It acts as a 'peel' only, no lower-bound RCE, no
1333// alignment. Useful to unroll loops that do no array accesses.
1334void PhaseIdealLoop::insert_pre_post_loops(IdealLoopTree *loop, Node_List &old_new, bool peel_only) {
1335
1336#ifndef PRODUCT
1337 if (TraceLoopOpts) {
1338 if (peel_only)
1339 tty->print("PeelMainPost ");
1340 else
1341 tty->print("PreMainPost ");
1342 loop->dump_head();
1343 }
1344#endif
1345 C->set_major_progress();
1346
1347 // Find common pieces of the loop being guarded with pre & post loops
1348 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1349 assert(main_head->is_normal_loop(), "");
1350 CountedLoopEndNode *main_end = main_head->loopexit();
1351 assert(main_end->outcnt() == 2, "1 true, 1 false path only");
1352
1353 Node *pre_header= main_head->in(LoopNode::EntryControl);
1354 Node *init = main_head->init_trip();
1355 Node *incr = main_end ->incr();
1356 Node *limit = main_end ->limit();
1357 Node *stride = main_end ->stride();
1358 Node *cmp = main_end ->cmp_node();
1359 BoolTest::mask b_test = main_end->test_trip();
1360
1361 // Need only 1 user of 'bol' because I will be hacking the loop bounds.
1362 Node *bol = main_end->in(CountedLoopEndNode::TestValue);
1363 if (bol->outcnt() != 1) {
1364 bol = bol->clone();
1365 register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl));
1366 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, bol);
1367 }
1368 // Need only 1 user of 'cmp' because I will be hacking the loop bounds.
1369 if (cmp->outcnt() != 1) {
1370 cmp = cmp->clone();
1371 register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl));
1372 _igvn.replace_input_of(bol, 1, cmp);
1373 }
1374
1375 // Add the post loop
1376 CountedLoopNode *post_head = NULL;
1377 Node *main_exit = insert_post_loop(loop, old_new, main_head, main_end, incr, limit, post_head);
1378
1379 //------------------------------
1380 // Step B: Create Pre-Loop.
1381
1382 // Step B1: Clone the loop body. The clone becomes the pre-loop. The main
1383 // loop pre-header illegally has 2 control users (old & new loops).
1384 LoopNode* outer_main_head = main_head;
1385 IdealLoopTree* outer_loop = loop;
1386 if (main_head->is_strip_mined()) {
1387 main_head->verify_strip_mined(1);
1388 outer_main_head = main_head->outer_loop();
1389 outer_loop = loop->_parent;
1390 assert(outer_loop->_head == outer_main_head, "broken loop tree");
1391 }
1392 uint dd_main_head = dom_depth(outer_main_head);
1393 clone_loop(loop, old_new, dd_main_head, ControlAroundStripMined);
1394 CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop();
1395 CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
1396 pre_head->set_pre_loop(main_head);
1397 Node *pre_incr = old_new[incr->_idx];
1398
1399 // Reduce the pre-loop trip count.
1400 pre_end->_prob = PROB_FAIR;
1401
1402 // Find the pre-loop normal exit.
1403 Node* pre_exit = pre_end->proj_out(false);
1404 assert(pre_exit->Opcode() == Op_IfFalse, "");
1405 IfFalseNode *new_pre_exit = new IfFalseNode(pre_end);
1406 _igvn.register_new_node_with_optimizer(new_pre_exit);
1407 set_idom(new_pre_exit, pre_end, dd_main_head);
1408 set_loop(new_pre_exit, outer_loop->_parent);
1409
1410 // Step B2: Build a zero-trip guard for the main-loop. After leaving the
1411 // pre-loop, the main-loop may not execute at all. Later in life this
1412 // zero-trip guard will become the minimum-trip guard when we unroll
1413 // the main-loop.
1414 Node *min_opaq = new Opaque1Node(C, limit);
1415 Node *min_cmp = new CmpINode(pre_incr, min_opaq);
1416 Node *min_bol = new BoolNode(min_cmp, b_test);
1417 register_new_node(min_opaq, new_pre_exit);
1418 register_new_node(min_cmp , new_pre_exit);
1419 register_new_node(min_bol , new_pre_exit);
1420
1421 // Build the IfNode (assume the main-loop is executed always).
1422 IfNode *min_iff = new IfNode(new_pre_exit, min_bol, PROB_ALWAYS, COUNT_UNKNOWN);
1423 _igvn.register_new_node_with_optimizer(min_iff);
1424 set_idom(min_iff, new_pre_exit, dd_main_head);
1425 set_loop(min_iff, outer_loop->_parent);
1426
1427 // Plug in the false-path, taken if we need to skip main-loop
1428 _igvn.hash_delete(pre_exit);
1429 pre_exit->set_req(0, min_iff);
1430 set_idom(pre_exit, min_iff, dd_main_head);
1431 set_idom(pre_exit->unique_ctrl_out(), min_iff, dd_main_head);
1432 // Make the true-path, must enter the main loop
1433 Node *min_taken = new IfTrueNode(min_iff);
1434 _igvn.register_new_node_with_optimizer(min_taken);
1435 set_idom(min_taken, min_iff, dd_main_head);
1436 set_loop(min_taken, outer_loop->_parent);
1437 // Plug in the true path
1438 _igvn.hash_delete(outer_main_head);
1439 outer_main_head->set_req(LoopNode::EntryControl, min_taken);
1440 set_idom(outer_main_head, min_taken, dd_main_head);
1441
1442 Arena *a = Thread::current()->resource_area();
1443 VectorSet visited(a);
1444 Node_Stack clones(a, main_head->back_control()->outcnt());
1445 // Step B3: Make the fall-in values to the main-loop come from the
1446 // fall-out values of the pre-loop.
1447 for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) {
1448 Node* main_phi = main_head->fast_out(i2);
1449 if (main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0) {
1450 Node *pre_phi = old_new[main_phi->_idx];
1451 Node *fallpre = clone_up_backedge_goo(pre_head->back_control(),
1452 main_head->skip_strip_mined()->in(LoopNode::EntryControl),
1453 pre_phi->in(LoopNode::LoopBackControl),
1454 visited, clones);
1455 _igvn.hash_delete(main_phi);
1456 main_phi->set_req(LoopNode::EntryControl, fallpre);
1457 }
1458 }
1459
1460 // Nodes inside the loop may be control dependent on a predicate
1461 // that was moved before the preloop. If the back branch of the main
1462 // or post loops becomes dead, those nodes won't be dependent on the
1463 // test that guards that loop nest anymore which could lead to an
1464 // incorrect array access because it executes independently of the
1465 // test that was guarding the loop nest. We add a special CastII on
1466 // the if branch that enters the loop, between the input induction
1467 // variable value and the induction variable Phi to preserve correct
1468 // dependencies.
1469
1470 // CastII for the main loop:
1471 Node* castii = cast_incr_before_loop(pre_incr, min_taken, main_head);
1472 assert(castii != NULL, "no castII inserted");
1473 Node* opaque_castii = new Opaque1Node(C, castii);
1474 register_new_node(opaque_castii, outer_main_head->in(LoopNode::EntryControl));
1475 duplicate_predicates(pre_head, castii, opaque_castii, outer_loop, outer_main_head, dd_main_head);
1476
1477 // Step B4: Shorten the pre-loop to run only 1 iteration (for now).
1478 // RCE and alignment may change this later.
1479 Node *cmp_end = pre_end->cmp_node();
1480 assert(cmp_end->in(2) == limit, "");
1481 Node *pre_limit = new AddINode(init, stride);
1482
1483 // Save the original loop limit in this Opaque1 node for
1484 // use by range check elimination.
1485 Node *pre_opaq = new Opaque1Node(C, pre_limit, limit);
1486
1487 register_new_node(pre_limit, pre_head->in(0));
1488 register_new_node(pre_opaq , pre_head->in(0));
1489
1490 // Since no other users of pre-loop compare, I can hack limit directly
1491 assert(cmp_end->outcnt() == 1, "no other users");
1492 _igvn.hash_delete(cmp_end);
1493 cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq);
1494
1495 // Special case for not-equal loop bounds:
1496 // Change pre loop test, main loop test, and the
1497 // main loop guard test to use lt or gt depending on stride
1498 // direction:
1499 // positive stride use <
1500 // negative stride use >
1501 //
1502 // not-equal test is kept for post loop to handle case
1503 // when init > limit when stride > 0 (and reverse).
1504
1505 if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) {
1506
1507 BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt;
1508 // Modify pre loop end condition
1509 Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1510 BoolNode* new_bol0 = new BoolNode(pre_bol->in(1), new_test);
1511 register_new_node(new_bol0, pre_head->in(0));
1512 _igvn.replace_input_of(pre_end, CountedLoopEndNode::TestValue, new_bol0);
1513 // Modify main loop guard condition
1514 assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay");
1515 BoolNode* new_bol1 = new BoolNode(min_bol->in(1), new_test);
1516 register_new_node(new_bol1, new_pre_exit);
1517 _igvn.hash_delete(min_iff);
1518 min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1);
1519 // Modify main loop end condition
1520 BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1521 BoolNode* new_bol2 = new BoolNode(main_bol->in(1), new_test);
1522 register_new_node(new_bol2, main_end->in(CountedLoopEndNode::TestControl));
1523 _igvn.replace_input_of(main_end, CountedLoopEndNode::TestValue, new_bol2);
1524 }
1525
1526 // Flag main loop
1527 main_head->set_main_loop();
1528 if (peel_only) {
1529 main_head->set_main_no_pre_loop();
1530 }
1531
1532 // Subtract a trip count for the pre-loop.
1533 main_head->set_trip_count(main_head->trip_count() - 1);
1534
1535 // It's difficult to be precise about the trip-counts
1536 // for the pre/post loops. They are usually very short,
1537 // so guess that 4 trips is a reasonable value.
1538 post_head->set_profile_trip_cnt(4.0);
1539 pre_head->set_profile_trip_cnt(4.0);
1540
1541 // Now force out all loop-invariant dominating tests. The optimizer
1542 // finds some, but we _know_ they are all useless.
1543 peeled_dom_test_elim(loop,old_new);
1544 loop->record_for_igvn();
1545}
1546
1547//------------------------------insert_vector_post_loop------------------------
1548// Insert a copy of the atomic unrolled vectorized main loop as a post loop,
1549// unroll_policy has already informed us that more unrolling is about to
1550// happen to the main loop. The resultant post loop will serve as a
1551// vectorized drain loop.
1552void PhaseIdealLoop::insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new) {
1553 if (!loop->_head->is_CountedLoop()) return;
1554
1555 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1556
1557 // only process vectorized main loops
1558 if (!cl->is_vectorized_loop() || !cl->is_main_loop()) return;
1559
1560 int slp_max_unroll_factor = cl->slp_max_unroll();
1561 int cur_unroll = cl->unrolled_count();
1562
1563 if (slp_max_unroll_factor == 0) return;
1564
1565 // only process atomic unroll vector loops (not super unrolled after vectorization)
1566 if (cur_unroll != slp_max_unroll_factor) return;
1567
1568 // we only ever process this one time
1569 if (cl->has_atomic_post_loop()) return;
1570
1571 if (!may_require_nodes(loop->est_loop_clone_sz(2))) {
1572 return;
1573 }
1574
1575#ifndef PRODUCT
1576 if (TraceLoopOpts) {
1577 tty->print("PostVector ");
1578 loop->dump_head();
1579 }
1580#endif
1581 C->set_major_progress();
1582
1583 // Find common pieces of the loop being guarded with pre & post loops
1584 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1585 CountedLoopEndNode *main_end = main_head->loopexit();
1586 // diagnostic to show loop end is not properly formed
1587 assert(main_end->outcnt() == 2, "1 true, 1 false path only");
1588
1589 // mark this loop as processed
1590 main_head->mark_has_atomic_post_loop();
1591
1592 Node *incr = main_end->incr();
1593 Node *limit = main_end->limit();
1594
1595 // In this case we throw away the result as we are not using it to connect anything else.
1596 CountedLoopNode *post_head = NULL;
1597 insert_post_loop(loop, old_new, main_head, main_end, incr, limit, post_head);
1598
1599 // It's difficult to be precise about the trip-counts
1600 // for post loops. They are usually very short,
1601 // so guess that unit vector trips is a reasonable value.
1602 post_head->set_profile_trip_cnt(cur_unroll);
1603
1604 // Now force out all loop-invariant dominating tests. The optimizer
1605 // finds some, but we _know_ they are all useless.
1606 peeled_dom_test_elim(loop, old_new);
1607 loop->record_for_igvn();
1608}
1609
1610
1611//-------------------------insert_scalar_rced_post_loop------------------------
1612// Insert a copy of the rce'd main loop as a post loop,
1613// We have not unrolled the main loop, so this is the right time to inject this.
1614// Later we will examine the partner of this post loop pair which still has range checks
1615// to see inject code which tests at runtime if the range checks are applicable.
1616void PhaseIdealLoop::insert_scalar_rced_post_loop(IdealLoopTree *loop, Node_List &old_new) {
1617 if (!loop->_head->is_CountedLoop()) return;
1618
1619 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1620
1621 // only process RCE'd main loops
1622 if (!cl->is_main_loop() || cl->range_checks_present()) return;
1623
1624#ifndef PRODUCT
1625 if (TraceLoopOpts) {
1626 tty->print("PostScalarRce ");
1627 loop->dump_head();
1628 }
1629#endif
1630 C->set_major_progress();
1631
1632 // Find common pieces of the loop being guarded with pre & post loops
1633 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
1634 CountedLoopEndNode *main_end = main_head->loopexit();
1635 // diagnostic to show loop end is not properly formed
1636 assert(main_end->outcnt() == 2, "1 true, 1 false path only");
1637
1638 Node *incr = main_end->incr();
1639 Node *limit = main_end->limit();
1640
1641 // In this case we throw away the result as we are not using it to connect anything else.
1642 CountedLoopNode *post_head = NULL;
1643 insert_post_loop(loop, old_new, main_head, main_end, incr, limit, post_head);
1644
1645 // It's difficult to be precise about the trip-counts
1646 // for post loops. They are usually very short,
1647 // so guess that unit vector trips is a reasonable value.
1648 post_head->set_profile_trip_cnt(4.0);
1649 post_head->set_is_rce_post_loop();
1650
1651 // Now force out all loop-invariant dominating tests. The optimizer
1652 // finds some, but we _know_ they are all useless.
1653 peeled_dom_test_elim(loop, old_new);
1654 loop->record_for_igvn();
1655}
1656
1657
1658//------------------------------insert_post_loop-------------------------------
1659// Insert post loops. Add a post loop to the given loop passed.
1660Node *PhaseIdealLoop::insert_post_loop(IdealLoopTree *loop, Node_List &old_new,
1661 CountedLoopNode *main_head, CountedLoopEndNode *main_end,
1662 Node *incr, Node *limit, CountedLoopNode *&post_head) {
1663 IfNode* outer_main_end = main_end;
1664 IdealLoopTree* outer_loop = loop;
1665 if (main_head->is_strip_mined()) {
1666 main_head->verify_strip_mined(1);
1667 outer_main_end = main_head->outer_loop_end();
1668 outer_loop = loop->_parent;
1669 assert(outer_loop->_head == main_head->in(LoopNode::EntryControl), "broken loop tree");
1670 }
1671
1672 //------------------------------
1673 // Step A: Create a new post-Loop.
1674 Node* main_exit = outer_main_end->proj_out(false);
1675 assert(main_exit->Opcode() == Op_IfFalse, "");
1676 int dd_main_exit = dom_depth(main_exit);
1677
1678 // Step A1: Clone the loop body of main. The clone becomes the post-loop.
1679 // The main loop pre-header illegally has 2 control users (old & new loops).
1680 clone_loop(loop, old_new, dd_main_exit, ControlAroundStripMined);
1681 assert(old_new[main_end->_idx]->Opcode() == Op_CountedLoopEnd, "");
1682 post_head = old_new[main_head->_idx]->as_CountedLoop();
1683 post_head->set_normal_loop();
1684 post_head->set_post_loop(main_head);
1685
1686 // Reduce the post-loop trip count.
1687 CountedLoopEndNode* post_end = old_new[main_end->_idx]->as_CountedLoopEnd();
1688 post_end->_prob = PROB_FAIR;
1689
1690 // Build the main-loop normal exit.
1691 IfFalseNode *new_main_exit = new IfFalseNode(outer_main_end);
1692 _igvn.register_new_node_with_optimizer(new_main_exit);
1693 set_idom(new_main_exit, outer_main_end, dd_main_exit);
1694 set_loop(new_main_exit, outer_loop->_parent);
1695
1696 // Step A2: Build a zero-trip guard for the post-loop. After leaving the
1697 // main-loop, the post-loop may not execute at all. We 'opaque' the incr
1698 // (the previous loop trip-counter exit value) because we will be changing
1699 // the exit value (via additional unrolling) so we cannot constant-fold away the zero
1700 // trip guard until all unrolling is done.
1701 Node *zer_opaq = new Opaque1Node(C, incr);
1702 Node *zer_cmp = new CmpINode(zer_opaq, limit);
1703 Node *zer_bol = new BoolNode(zer_cmp, main_end->test_trip());
1704 register_new_node(zer_opaq, new_main_exit);
1705 register_new_node(zer_cmp, new_main_exit);
1706 register_new_node(zer_bol, new_main_exit);
1707
1708 // Build the IfNode
1709 IfNode *zer_iff = new IfNode(new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN);
1710 _igvn.register_new_node_with_optimizer(zer_iff);
1711 set_idom(zer_iff, new_main_exit, dd_main_exit);
1712 set_loop(zer_iff, outer_loop->_parent);
1713
1714 // Plug in the false-path, taken if we need to skip this post-loop
1715 _igvn.replace_input_of(main_exit, 0, zer_iff);
1716 set_idom(main_exit, zer_iff, dd_main_exit);
1717 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit);
1718 // Make the true-path, must enter this post loop
1719 Node *zer_taken = new IfTrueNode(zer_iff);
1720 _igvn.register_new_node_with_optimizer(zer_taken);
1721 set_idom(zer_taken, zer_iff, dd_main_exit);
1722 set_loop(zer_taken, outer_loop->_parent);
1723 // Plug in the true path
1724 _igvn.hash_delete(post_head);
1725 post_head->set_req(LoopNode::EntryControl, zer_taken);
1726 set_idom(post_head, zer_taken, dd_main_exit);
1727
1728 Arena *a = Thread::current()->resource_area();
1729 VectorSet visited(a);
1730 Node_Stack clones(a, main_head->back_control()->outcnt());
1731 // Step A3: Make the fall-in values to the post-loop come from the
1732 // fall-out values of the main-loop.
1733 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
1734 Node* main_phi = main_head->fast_out(i);
1735 if (main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0) {
1736 Node *cur_phi = old_new[main_phi->_idx];
1737 Node *fallnew = clone_up_backedge_goo(main_head->back_control(),
1738 post_head->init_control(),
1739 main_phi->in(LoopNode::LoopBackControl),
1740 visited, clones);
1741 _igvn.hash_delete(cur_phi);
1742 cur_phi->set_req(LoopNode::EntryControl, fallnew);
1743 }
1744 }
1745
1746 // CastII for the new post loop:
1747 Node* castii = cast_incr_before_loop(zer_opaq->in(1), zer_taken, post_head);
1748 assert(castii != NULL, "no castII inserted");
1749
1750 return new_main_exit;
1751}
1752
1753//------------------------------is_invariant-----------------------------
1754// Return true if n is invariant
1755bool IdealLoopTree::is_invariant(Node* n) const {
1756 Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n;
1757 if (n_c->is_top()) return false;
1758 return !is_member(_phase->get_loop(n_c));
1759}
1760
1761void PhaseIdealLoop::update_skeleton_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con) {
1762 // Search for skeleton predicates and update them according to the new stride
1763 Node* entry = ctrl;
1764 Node* prev_proj = ctrl;
1765 LoopNode* outer_loop_head = loop_head->skip_strip_mined();
1766 IdealLoopTree* outer_loop = get_loop(outer_loop_head);
1767 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
1768 IfNode* iff = entry->in(0)->as_If();
1769 ProjNode* proj = iff->proj_out(1 - entry->as_Proj()->_con);
1770 if (proj->unique_ctrl_out()->Opcode() != Op_Halt) {
1771 break;
1772 }
1773 if (iff->in(1)->Opcode() == Op_Opaque4) {
1774 // Look for predicate with an Opaque1 node that can be used as a template
1775 if (!skeleton_predicate_has_opaque(iff)) {
1776 // No Opaque1 node? It's either the check for the first value
1777 // of the first iteration or the check for the last value of
1778 // the first iteration of an unrolled loop. We can't
1779 // tell. Kill it in any case.
1780 _igvn.replace_input_of(iff, 1, iff->in(1)->in(2));
1781 } else {
1782 // Add back the predicate for the value at the beginning of the first entry
1783 prev_proj = clone_skeleton_predicate(iff, init, entry, proj, ctrl, outer_loop, prev_proj);
1784 assert(!skeleton_predicate_has_opaque(prev_proj->in(0)->as_If()), "unexpected");
1785 // Compute the value of the loop induction variable at the end of the
1786 // first iteration of the unrolled loop: init + new_stride_con - init_inc
1787 int init_inc = stride_con/loop_head->unrolled_count();
1788 assert(init_inc != 0, "invalid loop increment");
1789 int new_stride_con = stride_con * 2;
1790 Node* max_value = _igvn.intcon(new_stride_con - init_inc);
1791 max_value = new AddINode(init, max_value);
1792 register_new_node(max_value, get_ctrl(iff->in(1)));
1793 prev_proj = clone_skeleton_predicate(iff, max_value, entry, proj, ctrl, outer_loop, prev_proj);
1794 assert(!skeleton_predicate_has_opaque(prev_proj->in(0)->as_If()), "unexpected");
1795 }
1796 }
1797 entry = entry->in(0)->in(0);
1798 }
1799 if (prev_proj != ctrl) {
1800 _igvn.replace_input_of(outer_loop_head, LoopNode::EntryControl, prev_proj);
1801 set_idom(outer_loop_head, prev_proj, dom_depth(outer_loop_head));
1802 }
1803}
1804
1805//------------------------------do_unroll--------------------------------------
1806// Unroll the loop body one step - make each trip do 2 iterations.
1807void PhaseIdealLoop::do_unroll(IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip) {
1808 assert(LoopUnrollLimit, "");
1809 CountedLoopNode *loop_head = loop->_head->as_CountedLoop();
1810 CountedLoopEndNode *loop_end = loop_head->loopexit();
1811#ifndef PRODUCT
1812 if (PrintOpto && VerifyLoopOptimizations) {
1813 tty->print("Unrolling ");
1814 loop->dump_head();
1815 } else if (TraceLoopOpts) {
1816 if (loop_head->trip_count() < (uint)LoopUnrollLimit) {
1817 tty->print("Unroll %d(%2d) ", loop_head->unrolled_count()*2, loop_head->trip_count());
1818 } else {
1819 tty->print("Unroll %d ", loop_head->unrolled_count()*2);
1820 }
1821 loop->dump_head();
1822 }
1823
1824 if (C->do_vector_loop() && (PrintOpto && (VerifyLoopOptimizations || TraceLoopOpts))) {
1825 Arena* arena = Thread::current()->resource_area();
1826 Node_Stack stack(arena, C->live_nodes() >> 2);
1827 Node_List rpo_list;
1828 VectorSet visited(arena);
1829 visited.set(loop_head->_idx);
1830 rpo(loop_head, stack, visited, rpo_list);
1831 dump(loop, rpo_list.size(), rpo_list);
1832 }
1833#endif
1834
1835 // Remember loop node count before unrolling to detect
1836 // if rounds of unroll,optimize are making progress
1837 loop_head->set_node_count_before_unroll(loop->_body.size());
1838
1839 Node *ctrl = loop_head->skip_strip_mined()->in(LoopNode::EntryControl);
1840 Node *limit = loop_head->limit();
1841 Node *init = loop_head->init_trip();
1842 Node *stride = loop_head->stride();
1843
1844 Node *opaq = NULL;
1845 if (adjust_min_trip) { // If not maximally unrolling, need adjustment
1846 // Search for zero-trip guard.
1847
1848 // Check the shape of the graph at the loop entry. If an inappropriate
1849 // graph shape is encountered, the compiler bails out loop unrolling;
1850 // compilation of the method will still succeed.
1851 if (!is_canonical_loop_entry(loop_head)) {
1852 return;
1853 }
1854 opaq = loop_head->skip_predicates()->in(0)->in(1)->in(1)->in(2);
1855 // Zero-trip test uses an 'opaque' node which is not shared.
1856 assert(opaq->outcnt() == 1 && opaq->in(1) == limit, "");
1857 }
1858
1859 C->set_major_progress();
1860
1861 Node* new_limit = NULL;
1862 int stride_con = stride->get_int();
1863 int stride_p = (stride_con > 0) ? stride_con : -stride_con;
1864 uint old_trip_count = loop_head->trip_count();
1865 // Verify that unroll policy result is still valid.
1866 assert(old_trip_count > 1 &&
1867 (!adjust_min_trip || stride_p <= (1<<3)*loop_head->unrolled_count()), "sanity");
1868
1869 update_skeleton_predicates(ctrl, loop_head, init, stride_con);
1870
1871 // Adjust loop limit to keep valid iterations number after unroll.
1872 // Use (limit - stride) instead of (((limit - init)/stride) & (-2))*stride
1873 // which may overflow.
1874 if (!adjust_min_trip) {
1875 assert(old_trip_count > 1 && (old_trip_count & 1) == 0,
1876 "odd trip count for maximally unroll");
1877 // Don't need to adjust limit for maximally unroll since trip count is even.
1878 } else if (loop_head->has_exact_trip_count() && init->is_Con()) {
1879 // Loop's limit is constant. Loop's init could be constant when pre-loop
1880 // become peeled iteration.
1881 jlong init_con = init->get_int();
1882 // We can keep old loop limit if iterations count stays the same:
1883 // old_trip_count == new_trip_count * 2
1884 // Note: since old_trip_count >= 2 then new_trip_count >= 1
1885 // so we also don't need to adjust zero trip test.
1886 jlong limit_con = limit->get_int();
1887 // (stride_con*2) not overflow since stride_con <= 8.
1888 int new_stride_con = stride_con * 2;
1889 int stride_m = new_stride_con - (stride_con > 0 ? 1 : -1);
1890 jlong trip_count = (limit_con - init_con + stride_m)/new_stride_con;
1891 // New trip count should satisfy next conditions.
1892 assert(trip_count > 0 && (julong)trip_count < (julong)max_juint/2, "sanity");
1893 uint new_trip_count = (uint)trip_count;
1894 adjust_min_trip = (old_trip_count != new_trip_count*2);
1895 }
1896
1897 if (adjust_min_trip) {
1898 // Step 2: Adjust the trip limit if it is called for.
1899 // The adjustment amount is -stride. Need to make sure if the
1900 // adjustment underflows or overflows, then the main loop is skipped.
1901 Node* cmp = loop_end->cmp_node();
1902 assert(cmp->in(2) == limit, "sanity");
1903 assert(opaq != NULL && opaq->in(1) == limit, "sanity");
1904
1905 // Verify that policy_unroll result is still valid.
1906 const TypeInt* limit_type = _igvn.type(limit)->is_int();
1907 assert(stride_con > 0 && ((limit_type->_hi - stride_con) < limit_type->_hi) ||
1908 stride_con < 0 && ((limit_type->_lo - stride_con) > limit_type->_lo),
1909 "sanity");
1910
1911 if (limit->is_Con()) {
1912 // The check in policy_unroll and the assert above guarantee
1913 // no underflow if limit is constant.
1914 new_limit = _igvn.intcon(limit->get_int() - stride_con);
1915 set_ctrl(new_limit, C->root());
1916 } else {
1917 // Limit is not constant.
1918 if (loop_head->unrolled_count() == 1) { // only for first unroll
1919 // Separate limit by Opaque node in case it is an incremented
1920 // variable from previous loop to avoid using pre-incremented
1921 // value which could increase register pressure.
1922 // Otherwise reorg_offsets() optimization will create a separate
1923 // Opaque node for each use of trip-counter and as result
1924 // zero trip guard limit will be different from loop limit.
1925 assert(has_ctrl(opaq), "should have it");
1926 Node* opaq_ctrl = get_ctrl(opaq);
1927 limit = new Opaque2Node(C, limit);
1928 register_new_node(limit, opaq_ctrl);
1929 }
1930 if ((stride_con > 0 && (java_subtract(limit_type->_lo, stride_con) < limit_type->_lo)) ||
1931 (stride_con < 0 && (java_subtract(limit_type->_hi, stride_con) > limit_type->_hi))) {
1932 // No underflow.
1933 new_limit = new SubINode(limit, stride);
1934 } else {
1935 // (limit - stride) may underflow.
1936 // Clamp the adjustment value with MININT or MAXINT:
1937 //
1938 // new_limit = limit-stride
1939 // if (stride > 0)
1940 // new_limit = (limit < new_limit) ? MININT : new_limit;
1941 // else
1942 // new_limit = (limit > new_limit) ? MAXINT : new_limit;
1943 //
1944 BoolTest::mask bt = loop_end->test_trip();
1945 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
1946 Node* adj_max = _igvn.intcon((stride_con > 0) ? min_jint : max_jint);
1947 set_ctrl(adj_max, C->root());
1948 Node* old_limit = NULL;
1949 Node* adj_limit = NULL;
1950 Node* bol = limit->is_CMove() ? limit->in(CMoveNode::Condition) : NULL;
1951 if (loop_head->unrolled_count() > 1 &&
1952 limit->is_CMove() && limit->Opcode() == Op_CMoveI &&
1953 limit->in(CMoveNode::IfTrue) == adj_max &&
1954 bol->as_Bool()->_test._test == bt &&
1955 bol->in(1)->Opcode() == Op_CmpI &&
1956 bol->in(1)->in(2) == limit->in(CMoveNode::IfFalse)) {
1957 // Loop was unrolled before.
1958 // Optimize the limit to avoid nested CMove:
1959 // use original limit as old limit.
1960 old_limit = bol->in(1)->in(1);
1961 // Adjust previous adjusted limit.
1962 adj_limit = limit->in(CMoveNode::IfFalse);
1963 adj_limit = new SubINode(adj_limit, stride);
1964 } else {
1965 old_limit = limit;
1966 adj_limit = new SubINode(limit, stride);
1967 }
1968 assert(old_limit != NULL && adj_limit != NULL, "");
1969 register_new_node(adj_limit, ctrl); // adjust amount
1970 Node* adj_cmp = new CmpINode(old_limit, adj_limit);
1971 register_new_node(adj_cmp, ctrl);
1972 Node* adj_bool = new BoolNode(adj_cmp, bt);
1973 register_new_node(adj_bool, ctrl);
1974 new_limit = new CMoveINode(adj_bool, adj_limit, adj_max, TypeInt::INT);
1975 }
1976 register_new_node(new_limit, ctrl);
1977 }
1978
1979 assert(new_limit != NULL, "");
1980 // Replace in loop test.
1981 assert(loop_end->in(1)->in(1) == cmp, "sanity");
1982 if (cmp->outcnt() == 1 && loop_end->in(1)->outcnt() == 1) {
1983 // Don't need to create new test since only one user.
1984 _igvn.hash_delete(cmp);
1985 cmp->set_req(2, new_limit);
1986 } else {
1987 // Create new test since it is shared.
1988 Node* ctrl2 = loop_end->in(0);
1989 Node* cmp2 = cmp->clone();
1990 cmp2->set_req(2, new_limit);
1991 register_new_node(cmp2, ctrl2);
1992 Node* bol2 = loop_end->in(1)->clone();
1993 bol2->set_req(1, cmp2);
1994 register_new_node(bol2, ctrl2);
1995 _igvn.replace_input_of(loop_end, 1, bol2);
1996 }
1997 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1998 // Make it a 1-trip test (means at least 2 trips).
1999
2000 // Guard test uses an 'opaque' node which is not shared. Hence I
2001 // can edit it's inputs directly. Hammer in the new limit for the
2002 // minimum-trip guard.
2003 assert(opaq->outcnt() == 1, "");
2004 _igvn.replace_input_of(opaq, 1, new_limit);
2005 }
2006
2007 // Adjust max trip count. The trip count is intentionally rounded
2008 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
2009 // the main, unrolled, part of the loop will never execute as it is protected
2010 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
2011 // and later determined that part of the unrolled loop was dead.
2012 loop_head->set_trip_count(old_trip_count / 2);
2013
2014 // Double the count of original iterations in the unrolled loop body.
2015 loop_head->double_unrolled_count();
2016
2017 // ---------
2018 // Step 4: Clone the loop body. Move it inside the loop. This loop body
2019 // represents the odd iterations; since the loop trips an even number of
2020 // times its backedge is never taken. Kill the backedge.
2021 uint dd = dom_depth(loop_head);
2022 clone_loop(loop, old_new, dd, IgnoreStripMined);
2023
2024 // Make backedges of the clone equal to backedges of the original.
2025 // Make the fall-in from the original come from the fall-out of the clone.
2026 for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) {
2027 Node* phi = loop_head->fast_out(j);
2028 if (phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0) {
2029 Node *newphi = old_new[phi->_idx];
2030 _igvn.hash_delete(phi);
2031 _igvn.hash_delete(newphi);
2032
2033 phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl));
2034 newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl));
2035 phi ->set_req(LoopNode::LoopBackControl, C->top());
2036 }
2037 }
2038 Node *clone_head = old_new[loop_head->_idx];
2039 _igvn.hash_delete(clone_head);
2040 loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl));
2041 clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl));
2042 loop_head ->set_req(LoopNode::LoopBackControl, C->top());
2043 loop->_head = clone_head; // New loop header
2044
2045 set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd);
2046 set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd);
2047
2048 // Kill the clone's backedge
2049 Node *newcle = old_new[loop_end->_idx];
2050 _igvn.hash_delete(newcle);
2051 Node *one = _igvn.intcon(1);
2052 set_ctrl(one, C->root());
2053 newcle->set_req(1, one);
2054 // Force clone into same loop body
2055 uint max = loop->_body.size();
2056 for (uint k = 0; k < max; k++) {
2057 Node *old = loop->_body.at(k);
2058 Node *nnn = old_new[old->_idx];
2059 loop->_body.push(nnn);
2060 if (!has_ctrl(old)) {
2061 set_loop(nnn, loop);
2062 }
2063 }
2064
2065 loop->record_for_igvn();
2066 loop_head->clear_strip_mined();
2067
2068#ifndef PRODUCT
2069 if (C->do_vector_loop() && (PrintOpto && (VerifyLoopOptimizations || TraceLoopOpts))) {
2070 tty->print("\nnew loop after unroll\n"); loop->dump_head();
2071 for (uint i = 0; i < loop->_body.size(); i++) {
2072 loop->_body.at(i)->dump();
2073 }
2074 if (C->clone_map().is_debug()) {
2075 tty->print("\nCloneMap\n");
2076 Dict* dict = C->clone_map().dict();
2077 DictI i(dict);
2078 tty->print_cr("Dict@%p[%d] = ", dict, dict->Size());
2079 for (int ii = 0; i.test(); ++i, ++ii) {
2080 NodeCloneInfo cl((uint64_t)dict->operator[]((void*)i._key));
2081 tty->print("%d->%d:%d,", (int)(intptr_t)i._key, cl.idx(), cl.gen());
2082 if (ii % 10 == 9) {
2083 tty->print_cr(" ");
2084 }
2085 }
2086 tty->print_cr(" ");
2087 }
2088 }
2089#endif
2090}
2091
2092//------------------------------do_maximally_unroll----------------------------
2093
2094void PhaseIdealLoop::do_maximally_unroll(IdealLoopTree *loop, Node_List &old_new) {
2095 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2096 assert(cl->has_exact_trip_count(), "trip count is not exact");
2097 assert(cl->trip_count() > 0, "");
2098#ifndef PRODUCT
2099 if (TraceLoopOpts) {
2100 tty->print("MaxUnroll %d ", cl->trip_count());
2101 loop->dump_head();
2102 }
2103#endif
2104
2105 // If loop is tripping an odd number of times, peel odd iteration
2106 if ((cl->trip_count() & 1) == 1) {
2107 do_peeling(loop, old_new);
2108 }
2109
2110 // Now its tripping an even number of times remaining. Double loop body.
2111 // Do not adjust pre-guards; they are not needed and do not exist.
2112 if (cl->trip_count() > 0) {
2113 assert((cl->trip_count() & 1) == 0, "missed peeling");
2114 do_unroll(loop, old_new, false);
2115 }
2116}
2117
2118void PhaseIdealLoop::mark_reductions(IdealLoopTree *loop) {
2119 if (SuperWordReductions == false) return;
2120
2121 CountedLoopNode* loop_head = loop->_head->as_CountedLoop();
2122 if (loop_head->unrolled_count() > 1) {
2123 return;
2124 }
2125
2126 Node* trip_phi = loop_head->phi();
2127 for (DUIterator_Fast imax, i = loop_head->fast_outs(imax); i < imax; i++) {
2128 Node* phi = loop_head->fast_out(i);
2129 if (phi->is_Phi() && phi->outcnt() > 0 && phi != trip_phi) {
2130 // For definitions which are loop inclusive and not tripcounts.
2131 Node* def_node = phi->in(LoopNode::LoopBackControl);
2132
2133 if (def_node != NULL) {
2134 Node* n_ctrl = get_ctrl(def_node);
2135 if (n_ctrl != NULL && loop->is_member(get_loop(n_ctrl))) {
2136 // Now test it to see if it fits the standard pattern for a reduction operator.
2137 int opc = def_node->Opcode();
2138 if (opc != ReductionNode::opcode(opc, def_node->bottom_type()->basic_type())
2139 || opc == Op_MinD || opc == Op_MinF || opc == Op_MaxD || opc == Op_MaxF) {
2140 if (!def_node->is_reduction()) { // Not marked yet
2141 // To be a reduction, the arithmetic node must have the phi as input and provide a def to it
2142 bool ok = false;
2143 for (unsigned j = 1; j < def_node->req(); j++) {
2144 Node* in = def_node->in(j);
2145 if (in == phi) {
2146 ok = true;
2147 break;
2148 }
2149 }
2150
2151 // do nothing if we did not match the initial criteria
2152 if (ok == false) {
2153 continue;
2154 }
2155
2156 // The result of the reduction must not be used in the loop
2157 for (DUIterator_Fast imax, i = def_node->fast_outs(imax); i < imax && ok; i++) {
2158 Node* u = def_node->fast_out(i);
2159 if (!loop->is_member(get_loop(ctrl_or_self(u)))) {
2160 continue;
2161 }
2162 if (u == phi) {
2163 continue;
2164 }
2165 ok = false;
2166 }
2167
2168 // iff the uses conform
2169 if (ok) {
2170 def_node->add_flag(Node::Flag_is_reduction);
2171 loop_head->mark_has_reductions();
2172 }
2173 }
2174 }
2175 }
2176 }
2177 }
2178 }
2179}
2180
2181//------------------------------adjust_limit-----------------------------------
2182// Helper function for add_constraint().
2183Node* PhaseIdealLoop::adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl, bool round_up) {
2184 // Compute "I :: (limit-offset)/scale"
2185 Node *con = new SubINode(rc_limit, offset);
2186 register_new_node(con, pre_ctrl);
2187 Node *X = new DivINode(0, con, scale);
2188 register_new_node(X, pre_ctrl);
2189
2190 // When the absolute value of scale is greater than one, the integer
2191 // division may round limit down so add one to the limit.
2192 if (round_up) {
2193 X = new AddINode(X, _igvn.intcon(1));
2194 register_new_node(X, pre_ctrl);
2195 }
2196
2197 // Adjust loop limit
2198 loop_limit = (stride_con > 0)
2199 ? (Node*)(new MinINode(loop_limit, X))
2200 : (Node*)(new MaxINode(loop_limit, X));
2201 register_new_node(loop_limit, pre_ctrl);
2202 return loop_limit;
2203}
2204
2205//------------------------------add_constraint---------------------------------
2206// Constrain the main loop iterations so the conditions:
2207// low_limit <= scale_con * I + offset < upper_limit
2208// always holds true. That is, either increase the number of iterations in
2209// the pre-loop or the post-loop until the condition holds true in the main
2210// loop. Stride, scale, offset and limit are all loop invariant. Further,
2211// stride and scale are constants (offset and limit often are).
2212void PhaseIdealLoop::add_constraint(int stride_con, int scale_con, Node *offset, Node *low_limit, Node *upper_limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit) {
2213 // For positive stride, the pre-loop limit always uses a MAX function
2214 // and the main loop a MIN function. For negative stride these are
2215 // reversed.
2216
2217 // Also for positive stride*scale the affine function is increasing, so the
2218 // pre-loop must check for underflow and the post-loop for overflow.
2219 // Negative stride*scale reverses this; pre-loop checks for overflow and
2220 // post-loop for underflow.
2221
2222 Node *scale = _igvn.intcon(scale_con);
2223 set_ctrl(scale, C->root());
2224
2225 if ((stride_con^scale_con) >= 0) { // Use XOR to avoid overflow
2226 // The overflow limit: scale*I+offset < upper_limit
2227 // For main-loop compute
2228 // ( if (scale > 0) /* and stride > 0 */
2229 // I < (upper_limit-offset)/scale
2230 // else /* scale < 0 and stride < 0 */
2231 // I > (upper_limit-offset)/scale
2232 // )
2233 //
2234 // (upper_limit-offset) may overflow or underflow.
2235 // But it is fine since main loop will either have
2236 // less iterations or will be skipped in such case.
2237 *main_limit = adjust_limit(stride_con, scale, offset, upper_limit, *main_limit, pre_ctrl, false);
2238
2239 // The underflow limit: low_limit <= scale*I+offset.
2240 // For pre-loop compute
2241 // NOT(scale*I+offset >= low_limit)
2242 // scale*I+offset < low_limit
2243 // ( if (scale > 0) /* and stride > 0 */
2244 // I < (low_limit-offset)/scale
2245 // else /* scale < 0 and stride < 0 */
2246 // I > (low_limit-offset)/scale
2247 // )
2248
2249 if (low_limit->get_int() == -max_jint) {
2250 // We need this guard when scale*pre_limit+offset >= limit
2251 // due to underflow. So we need execute pre-loop until
2252 // scale*I+offset >= min_int. But (min_int-offset) will
2253 // underflow when offset > 0 and X will be > original_limit
2254 // when stride > 0. To avoid it we replace positive offset with 0.
2255 //
2256 // Also (min_int+1 == -max_int) is used instead of min_int here
2257 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
2258 Node* shift = _igvn.intcon(31);
2259 set_ctrl(shift, C->root());
2260 Node* sign = new RShiftINode(offset, shift);
2261 register_new_node(sign, pre_ctrl);
2262 offset = new AndINode(offset, sign);
2263 register_new_node(offset, pre_ctrl);
2264 } else {
2265 assert(low_limit->get_int() == 0, "wrong low limit for range check");
2266 // The only problem we have here when offset == min_int
2267 // since (0-min_int) == min_int. It may be fine for stride > 0
2268 // but for stride < 0 X will be < original_limit. To avoid it
2269 // max(pre_limit, original_limit) is used in do_range_check().
2270 }
2271 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
2272 *pre_limit = adjust_limit((-stride_con), scale, offset, low_limit, *pre_limit, pre_ctrl,
2273 scale_con > 1 && stride_con > 0);
2274
2275 } else { // stride_con*scale_con < 0
2276 // For negative stride*scale pre-loop checks for overflow and
2277 // post-loop for underflow.
2278 //
2279 // The overflow limit: scale*I+offset < upper_limit
2280 // For pre-loop compute
2281 // NOT(scale*I+offset < upper_limit)
2282 // scale*I+offset >= upper_limit
2283 // scale*I+offset+1 > upper_limit
2284 // ( if (scale < 0) /* and stride > 0 */
2285 // I < (upper_limit-(offset+1))/scale
2286 // else /* scale > 0 and stride < 0 */
2287 // I > (upper_limit-(offset+1))/scale
2288 // )
2289 //
2290 // (upper_limit-offset-1) may underflow or overflow.
2291 // To avoid it min(pre_limit, original_limit) is used
2292 // in do_range_check() for stride > 0 and max() for < 0.
2293 Node *one = _igvn.intcon(1);
2294 set_ctrl(one, C->root());
2295
2296 Node *plus_one = new AddINode(offset, one);
2297 register_new_node(plus_one, pre_ctrl);
2298 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
2299 *pre_limit = adjust_limit((-stride_con), scale, plus_one, upper_limit, *pre_limit, pre_ctrl,
2300 scale_con < -1 && stride_con > 0);
2301
2302 if (low_limit->get_int() == -max_jint) {
2303 // We need this guard when scale*main_limit+offset >= limit
2304 // due to underflow. So we need execute main-loop while
2305 // scale*I+offset+1 > min_int. But (min_int-offset-1) will
2306 // underflow when (offset+1) > 0 and X will be < main_limit
2307 // when scale < 0 (and stride > 0). To avoid it we replace
2308 // positive (offset+1) with 0.
2309 //
2310 // Also (min_int+1 == -max_int) is used instead of min_int here
2311 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
2312 Node* shift = _igvn.intcon(31);
2313 set_ctrl(shift, C->root());
2314 Node* sign = new RShiftINode(plus_one, shift);
2315 register_new_node(sign, pre_ctrl);
2316 plus_one = new AndINode(plus_one, sign);
2317 register_new_node(plus_one, pre_ctrl);
2318 } else {
2319 assert(low_limit->get_int() == 0, "wrong low limit for range check");
2320 // The only problem we have here when offset == max_int
2321 // since (max_int+1) == min_int and (0-min_int) == min_int.
2322 // But it is fine since main loop will either have
2323 // less iterations or will be skipped in such case.
2324 }
2325 // The underflow limit: low_limit <= scale*I+offset.
2326 // For main-loop compute
2327 // scale*I+offset+1 > low_limit
2328 // ( if (scale < 0) /* and stride > 0 */
2329 // I < (low_limit-(offset+1))/scale
2330 // else /* scale > 0 and stride < 0 */
2331 // I > (low_limit-(offset+1))/scale
2332 // )
2333
2334 *main_limit = adjust_limit(stride_con, scale, plus_one, low_limit, *main_limit, pre_ctrl,
2335 false);
2336 }
2337}
2338
2339
2340//------------------------------is_scaled_iv---------------------------------
2341// Return true if exp is a constant times an induction var
2342bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) {
2343 if (exp == iv) {
2344 if (p_scale != NULL) {
2345 *p_scale = 1;
2346 }
2347 return true;
2348 }
2349 int opc = exp->Opcode();
2350 if (opc == Op_MulI) {
2351 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
2352 if (p_scale != NULL) {
2353 *p_scale = exp->in(2)->get_int();
2354 }
2355 return true;
2356 }
2357 if (exp->in(2) == iv && exp->in(1)->is_Con()) {
2358 if (p_scale != NULL) {
2359 *p_scale = exp->in(1)->get_int();
2360 }
2361 return true;
2362 }
2363 } else if (opc == Op_LShiftI) {
2364 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
2365 if (p_scale != NULL) {
2366 *p_scale = 1 << exp->in(2)->get_int();
2367 }
2368 return true;
2369 }
2370 }
2371 return false;
2372}
2373
2374//-----------------------------is_scaled_iv_plus_offset------------------------------
2375// Return true if exp is a simple induction variable expression: k1*iv + (invar + k2)
2376bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) {
2377 if (is_scaled_iv(exp, iv, p_scale)) {
2378 if (p_offset != NULL) {
2379 Node *zero = _igvn.intcon(0);
2380 set_ctrl(zero, C->root());
2381 *p_offset = zero;
2382 }
2383 return true;
2384 }
2385 int opc = exp->Opcode();
2386 if (opc == Op_AddI) {
2387 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
2388 if (p_offset != NULL) {
2389 *p_offset = exp->in(2);
2390 }
2391 return true;
2392 }
2393 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
2394 if (p_offset != NULL) {
2395 *p_offset = exp->in(1);
2396 }
2397 return true;
2398 }
2399 if (exp->in(2)->is_Con()) {
2400 Node* offset2 = NULL;
2401 if (depth < 2 &&
2402 is_scaled_iv_plus_offset(exp->in(1), iv, p_scale,
2403 p_offset != NULL ? &offset2 : NULL, depth+1)) {
2404 if (p_offset != NULL) {
2405 Node *ctrl_off2 = get_ctrl(offset2);
2406 Node* offset = new AddINode(offset2, exp->in(2));
2407 register_new_node(offset, ctrl_off2);
2408 *p_offset = offset;
2409 }
2410 return true;
2411 }
2412 }
2413 } else if (opc == Op_SubI) {
2414 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
2415 if (p_offset != NULL) {
2416 Node *zero = _igvn.intcon(0);
2417 set_ctrl(zero, C->root());
2418 Node *ctrl_off = get_ctrl(exp->in(2));
2419 Node* offset = new SubINode(zero, exp->in(2));
2420 register_new_node(offset, ctrl_off);
2421 *p_offset = offset;
2422 }
2423 return true;
2424 }
2425 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
2426 if (p_offset != NULL) {
2427 *p_scale *= -1;
2428 *p_offset = exp->in(1);
2429 }
2430 return true;
2431 }
2432 }
2433 return false;
2434}
2435
2436// Same as PhaseIdealLoop::duplicate_predicates() but for range checks
2437// eliminated by iteration splitting.
2438Node* PhaseIdealLoop::add_range_check_predicate(IdealLoopTree* loop, CountedLoopNode* cl,
2439 Node* predicate_proj, int scale_con, Node* offset,
2440 Node* limit, jint stride_con, Node* value) {
2441 bool overflow = false;
2442 BoolNode* bol = rc_predicate(loop, predicate_proj, scale_con, offset, value, NULL, stride_con, limit, (stride_con > 0) != (scale_con > 0), overflow);
2443 Node* opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1));
2444 register_new_node(opaque_bol, predicate_proj);
2445 IfNode* new_iff = NULL;
2446 if (overflow) {
2447 new_iff = new IfNode(predicate_proj, opaque_bol, PROB_MAX, COUNT_UNKNOWN);
2448 } else {
2449 new_iff = new RangeCheckNode(predicate_proj, opaque_bol, PROB_MAX, COUNT_UNKNOWN);
2450 }
2451 register_control(new_iff, loop->_parent, predicate_proj);
2452 Node* iffalse = new IfFalseNode(new_iff);
2453 register_control(iffalse, _ltree_root, new_iff);
2454 ProjNode* iftrue = new IfTrueNode(new_iff);
2455 register_control(iftrue, loop->_parent, new_iff);
2456 Node *frame = new ParmNode(C->start(), TypeFunc::FramePtr);
2457 register_new_node(frame, C->start());
2458 Node* halt = new HaltNode(iffalse, frame);
2459 register_control(halt, _ltree_root, iffalse);
2460 C->root()->add_req(halt);
2461 return iftrue;
2462}
2463
2464//------------------------------do_range_check---------------------------------
2465// Eliminate range-checks and other trip-counter vs loop-invariant tests.
2466int PhaseIdealLoop::do_range_check(IdealLoopTree *loop, Node_List &old_new) {
2467#ifndef PRODUCT
2468 if (PrintOpto && VerifyLoopOptimizations) {
2469 tty->print("Range Check Elimination ");
2470 loop->dump_head();
2471 } else if (TraceLoopOpts) {
2472 tty->print("RangeCheck ");
2473 loop->dump_head();
2474 }
2475#endif
2476
2477 assert(RangeCheckElimination, "");
2478 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2479 // If we fail before trying to eliminate range checks, set multiversion state
2480 int closed_range_checks = 1;
2481
2482 // protect against stride not being a constant
2483 if (!cl->stride_is_con()) {
2484 return closed_range_checks;
2485 }
2486 // Find the trip counter; we are iteration splitting based on it
2487 Node *trip_counter = cl->phi();
2488 // Find the main loop limit; we will trim it's iterations
2489 // to not ever trip end tests
2490 Node *main_limit = cl->limit();
2491
2492 // Check graph shape. Cannot optimize a loop if zero-trip
2493 // Opaque1 node is optimized away and then another round
2494 // of loop opts attempted.
2495 if (!is_canonical_loop_entry(cl)) {
2496 return closed_range_checks;
2497 }
2498
2499 // Need to find the main-loop zero-trip guard
2500 Node *ctrl = cl->skip_predicates();
2501 Node *iffm = ctrl->in(0);
2502 Node *opqzm = iffm->in(1)->in(1)->in(2);
2503 assert(opqzm->in(1) == main_limit, "do not understand situation");
2504
2505 // Find the pre-loop limit; we will expand its iterations to
2506 // not ever trip low tests.
2507 Node *p_f = iffm->in(0);
2508 // pre loop may have been optimized out
2509 if (p_f->Opcode() != Op_IfFalse) {
2510 return closed_range_checks;
2511 }
2512 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
2513 assert(pre_end->loopnode()->is_pre_loop(), "");
2514 Node *pre_opaq1 = pre_end->limit();
2515 // Occasionally it's possible for a pre-loop Opaque1 node to be
2516 // optimized away and then another round of loop opts attempted.
2517 // We can not optimize this particular loop in that case.
2518 if (pre_opaq1->Opcode() != Op_Opaque1) {
2519 return closed_range_checks;
2520 }
2521 Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
2522 Node *pre_limit = pre_opaq->in(1);
2523
2524 // Where do we put new limit calculations
2525 Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
2526
2527 // Ensure the original loop limit is available from the
2528 // pre-loop Opaque1 node.
2529 Node *orig_limit = pre_opaq->original_loop_limit();
2530 if (orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP) {
2531 return closed_range_checks;
2532 }
2533 // Must know if its a count-up or count-down loop
2534
2535 int stride_con = cl->stride_con();
2536 Node *zero = _igvn.intcon(0);
2537 Node *one = _igvn.intcon(1);
2538 // Use symmetrical int range [-max_jint,max_jint]
2539 Node *mini = _igvn.intcon(-max_jint);
2540 set_ctrl(zero, C->root());
2541 set_ctrl(one, C->root());
2542 set_ctrl(mini, C->root());
2543
2544 // Range checks that do not dominate the loop backedge (ie.
2545 // conditionally executed) can lengthen the pre loop limit beyond
2546 // the original loop limit. To prevent this, the pre limit is
2547 // (for stride > 0) MINed with the original loop limit (MAXed
2548 // stride < 0) when some range_check (rc) is conditionally
2549 // executed.
2550 bool conditional_rc = false;
2551
2552 // Count number of range checks and reduce by load range limits, if zero,
2553 // the loop is in canonical form to multiversion.
2554 closed_range_checks = 0;
2555
2556 Node* predicate_proj = cl->skip_strip_mined()->in(LoopNode::EntryControl);
2557 assert(predicate_proj->is_Proj() && predicate_proj->in(0)->is_If(), "if projection only");
2558
2559 // Check loop body for tests of trip-counter plus loop-invariant vs loop-variant.
2560 for (uint i = 0; i < loop->_body.size(); i++) {
2561 Node *iff = loop->_body[i];
2562 if (iff->Opcode() == Op_If ||
2563 iff->Opcode() == Op_RangeCheck) { // Test?
2564 // Test is an IfNode, has 2 projections. If BOTH are in the loop
2565 // we need loop unswitching instead of iteration splitting.
2566 closed_range_checks++;
2567 Node *exit = loop->is_loop_exit(iff);
2568 if (!exit) continue;
2569 int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0;
2570
2571 // Get boolean condition to test
2572 Node *i1 = iff->in(1);
2573 if (!i1->is_Bool()) continue;
2574 BoolNode *bol = i1->as_Bool();
2575 BoolTest b_test = bol->_test;
2576 // Flip sense of test if exit condition is flipped
2577 if (flip) {
2578 b_test = b_test.negate();
2579 }
2580 // Get compare
2581 Node *cmp = bol->in(1);
2582
2583 // Look for trip_counter + offset vs limit
2584 Node *rc_exp = cmp->in(1);
2585 Node *limit = cmp->in(2);
2586 int scale_con= 1; // Assume trip counter not scaled
2587
2588 Node *limit_c = get_ctrl(limit);
2589 if (loop->is_member(get_loop(limit_c))) {
2590 // Compare might have operands swapped; commute them
2591 b_test = b_test.commute();
2592 rc_exp = cmp->in(2);
2593 limit = cmp->in(1);
2594 limit_c = get_ctrl(limit);
2595 if (loop->is_member(get_loop(limit_c))) {
2596 continue; // Both inputs are loop varying; cannot RCE
2597 }
2598 }
2599 // Here we know 'limit' is loop invariant
2600
2601 // 'limit' maybe pinned below the zero trip test (probably from a
2602 // previous round of rce), in which case, it can't be used in the
2603 // zero trip test expression which must occur before the zero test's if.
2604 if (is_dominator(ctrl, limit_c)) {
2605 continue; // Don't rce this check but continue looking for other candidates.
2606 }
2607
2608 // Check for scaled induction variable plus an offset
2609 Node *offset = NULL;
2610
2611 if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) {
2612 continue;
2613 }
2614
2615 Node *offset_c = get_ctrl(offset);
2616 if (loop->is_member(get_loop(offset_c))) {
2617 continue; // Offset is not really loop invariant
2618 }
2619 // Here we know 'offset' is loop invariant.
2620
2621 // As above for the 'limit', the 'offset' maybe pinned below the
2622 // zero trip test.
2623 if (is_dominator(ctrl, offset_c)) {
2624 continue; // Don't rce this check but continue looking for other candidates.
2625 }
2626#ifdef ASSERT
2627 if (TraceRangeLimitCheck) {
2628 tty->print_cr("RC bool node%s", flip ? " flipped:" : ":");
2629 bol->dump(2);
2630 }
2631#endif
2632 // At this point we have the expression as:
2633 // scale_con * trip_counter + offset :: limit
2634 // where scale_con, offset and limit are loop invariant. Trip_counter
2635 // monotonically increases by stride_con, a constant. Both (or either)
2636 // stride_con and scale_con can be negative which will flip about the
2637 // sense of the test.
2638
2639 // Adjust pre and main loop limits to guard the correct iteration set
2640 if (cmp->Opcode() == Op_CmpU) { // Unsigned compare is really 2 tests
2641 if (b_test._test == BoolTest::lt) { // Range checks always use lt
2642 // The underflow and overflow limits: 0 <= scale*I+offset < limit
2643 add_constraint(stride_con, scale_con, offset, zero, limit, pre_ctrl, &pre_limit, &main_limit);
2644 // (0-offset)/scale could be outside of loop iterations range.
2645 conditional_rc = true;
2646 Node* init = cl->init_trip();
2647 Node* opaque_init = new Opaque1Node(C, init);
2648 register_new_node(opaque_init, predicate_proj);
2649 // template predicate so it can be updated on next unrolling
2650 predicate_proj = add_range_check_predicate(loop, cl, predicate_proj, scale_con, offset, limit, stride_con, opaque_init);
2651 assert(skeleton_predicate_has_opaque(predicate_proj->in(0)->as_If()), "unexpected");
2652 // predicate on first value of first iteration
2653 predicate_proj = add_range_check_predicate(loop, cl, predicate_proj, scale_con, offset, limit, stride_con, init);
2654 assert(!skeleton_predicate_has_opaque(predicate_proj->in(0)->as_If()), "unexpected");
2655 int init_inc = stride_con/cl->unrolled_count();
2656 assert(init_inc != 0, "invalid loop increment");
2657 Node* max_value = _igvn.intcon(stride_con - init_inc);
2658 max_value = new AddINode(init, max_value);
2659 register_new_node(max_value, predicate_proj);
2660 // predicate on last value of first iteration (in case unrolling has already happened)
2661 predicate_proj = add_range_check_predicate(loop, cl, predicate_proj, scale_con, offset, limit, stride_con, max_value);
2662 assert(!skeleton_predicate_has_opaque(predicate_proj->in(0)->as_If()), "unexpected");
2663 } else {
2664 if (PrintOpto) {
2665 tty->print_cr("missed RCE opportunity");
2666 }
2667 continue; // In release mode, ignore it
2668 }
2669 } else { // Otherwise work on normal compares
2670 switch(b_test._test) {
2671 case BoolTest::gt:
2672 // Fall into GE case
2673 case BoolTest::ge:
2674 // Convert (I*scale+offset) >= Limit to (I*(-scale)+(-offset)) <= -Limit
2675 scale_con = -scale_con;
2676 offset = new SubINode(zero, offset);
2677 register_new_node(offset, pre_ctrl);
2678 limit = new SubINode(zero, limit);
2679 register_new_node(limit, pre_ctrl);
2680 // Fall into LE case
2681 case BoolTest::le:
2682 if (b_test._test != BoolTest::gt) {
2683 // Convert X <= Y to X < Y+1
2684 limit = new AddINode(limit, one);
2685 register_new_node(limit, pre_ctrl);
2686 }
2687 // Fall into LT case
2688 case BoolTest::lt:
2689 // The underflow and overflow limits: MIN_INT <= scale*I+offset < limit
2690 // Note: (MIN_INT+1 == -MAX_INT) is used instead of MIN_INT here
2691 // to avoid problem with scale == -1: MIN_INT/(-1) == MIN_INT.
2692 add_constraint(stride_con, scale_con, offset, mini, limit, pre_ctrl, &pre_limit, &main_limit);
2693 // ((MIN_INT+1)-offset)/scale could be outside of loop iterations range.
2694 // Note: negative offset is replaced with 0 but (MIN_INT+1)/scale could
2695 // still be outside of loop range.
2696 conditional_rc = true;
2697 break;
2698 default:
2699 if (PrintOpto) {
2700 tty->print_cr("missed RCE opportunity");
2701 }
2702 continue; // Unhandled case
2703 }
2704 }
2705
2706 // Kill the eliminated test
2707 C->set_major_progress();
2708 Node *kill_con = _igvn.intcon(1-flip);
2709 set_ctrl(kill_con, C->root());
2710 _igvn.replace_input_of(iff, 1, kill_con);
2711 // Find surviving projection
2712 assert(iff->is_If(), "");
2713 ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip);
2714 // Find loads off the surviving projection; remove their control edge
2715 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
2716 Node* cd = dp->fast_out(i); // Control-dependent node
2717 if (cd->is_Load() && cd->depends_only_on_test()) { // Loads can now float around in the loop
2718 // Allow the load to float around in the loop, or before it
2719 // but NOT before the pre-loop.
2720 _igvn.replace_input_of(cd, 0, ctrl); // ctrl, not NULL
2721 --i;
2722 --imax;
2723 }
2724 }
2725 if (limit->Opcode() == Op_LoadRange) {
2726 closed_range_checks--;
2727 }
2728 } // End of is IF
2729 }
2730 if (predicate_proj != cl->skip_strip_mined()->in(LoopNode::EntryControl)) {
2731 _igvn.replace_input_of(cl->skip_strip_mined(), LoopNode::EntryControl, predicate_proj);
2732 set_idom(cl->skip_strip_mined(), predicate_proj, dom_depth(cl->skip_strip_mined()));
2733 }
2734
2735 // Update loop limits
2736 if (conditional_rc) {
2737 pre_limit = (stride_con > 0) ? (Node*)new MinINode(pre_limit, orig_limit)
2738 : (Node*)new MaxINode(pre_limit, orig_limit);
2739 register_new_node(pre_limit, pre_ctrl);
2740 }
2741 _igvn.replace_input_of(pre_opaq, 1, pre_limit);
2742
2743 // Note:: we are making the main loop limit no longer precise;
2744 // need to round up based on stride.
2745 cl->set_nonexact_trip_count();
2746 Node *main_cle = cl->loopexit();
2747 Node *main_bol = main_cle->in(1);
2748 // Hacking loop bounds; need private copies of exit test
2749 if (main_bol->outcnt() > 1) { // BoolNode shared?
2750 main_bol = main_bol->clone(); // Clone a private BoolNode
2751 register_new_node(main_bol, main_cle->in(0));
2752 _igvn.replace_input_of(main_cle, 1, main_bol);
2753 }
2754 Node *main_cmp = main_bol->in(1);
2755 if (main_cmp->outcnt() > 1) { // CmpNode shared?
2756 main_cmp = main_cmp->clone(); // Clone a private CmpNode
2757 register_new_node(main_cmp, main_cle->in(0));
2758 _igvn.replace_input_of(main_bol, 1, main_cmp);
2759 }
2760 // Hack the now-private loop bounds
2761 _igvn.replace_input_of(main_cmp, 2, main_limit);
2762 // The OpaqueNode is unshared by design
2763 assert(opqzm->outcnt() == 1, "cannot hack shared node");
2764 _igvn.replace_input_of(opqzm, 1, main_limit);
2765
2766 return closed_range_checks;
2767}
2768
2769//------------------------------has_range_checks-------------------------------
2770// Check to see if RCE cleaned the current loop of range-checks.
2771void PhaseIdealLoop::has_range_checks(IdealLoopTree *loop) {
2772 assert(RangeCheckElimination, "");
2773
2774 // skip if not a counted loop
2775 if (!loop->is_counted()) return;
2776
2777 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2778
2779 // skip this loop if it is already checked
2780 if (cl->has_been_range_checked()) return;
2781
2782 // Now check for existence of range checks
2783 for (uint i = 0; i < loop->_body.size(); i++) {
2784 Node *iff = loop->_body[i];
2785 int iff_opc = iff->Opcode();
2786 if (iff_opc == Op_If || iff_opc == Op_RangeCheck) {
2787 cl->mark_has_range_checks();
2788 break;
2789 }
2790 }
2791 cl->set_has_been_range_checked();
2792}
2793
2794//-------------------------multi_version_post_loops----------------------------
2795// Check the range checks that remain, if simple, use the bounds to guard
2796// which version to a post loop we execute, one with range checks or one without
2797bool PhaseIdealLoop::multi_version_post_loops(IdealLoopTree *rce_loop, IdealLoopTree *legacy_loop) {
2798 bool multi_version_succeeded = false;
2799 assert(RangeCheckElimination, "");
2800 CountedLoopNode *legacy_cl = legacy_loop->_head->as_CountedLoop();
2801 assert(legacy_cl->is_post_loop(), "");
2802
2803 // Check for existence of range checks using the unique instance to make a guard with
2804 Unique_Node_List worklist;
2805 for (uint i = 0; i < legacy_loop->_body.size(); i++) {
2806 Node *iff = legacy_loop->_body[i];
2807 int iff_opc = iff->Opcode();
2808 if (iff_opc == Op_If || iff_opc == Op_RangeCheck) {
2809 worklist.push(iff);
2810 }
2811 }
2812
2813 // Find RCE'd post loop so that we can stage its guard.
2814 if (!is_canonical_loop_entry(legacy_cl)) return multi_version_succeeded;
2815 Node* ctrl = legacy_cl->in(LoopNode::EntryControl);
2816 Node* iffm = ctrl->in(0);
2817
2818 // Now we test that both the post loops are connected
2819 Node* post_loop_region = iffm->in(0);
2820 if (post_loop_region == NULL) return multi_version_succeeded;
2821 if (!post_loop_region->is_Region()) return multi_version_succeeded;
2822 Node* covering_region = post_loop_region->in(RegionNode::Control+1);
2823 if (covering_region == NULL) return multi_version_succeeded;
2824 if (!covering_region->is_Region()) return multi_version_succeeded;
2825 Node* p_f = covering_region->in(RegionNode::Control);
2826 if (p_f == NULL) return multi_version_succeeded;
2827 if (!p_f->is_IfFalse()) return multi_version_succeeded;
2828 if (!p_f->in(0)->is_CountedLoopEnd()) return multi_version_succeeded;
2829 CountedLoopEndNode* rce_loop_end = p_f->in(0)->as_CountedLoopEnd();
2830 if (rce_loop_end == NULL) return multi_version_succeeded;
2831 CountedLoopNode* rce_cl = rce_loop_end->loopnode();
2832 if (rce_cl == NULL || !rce_cl->is_post_loop()) return multi_version_succeeded;
2833 CountedLoopNode *known_rce_cl = rce_loop->_head->as_CountedLoop();
2834 if (rce_cl != known_rce_cl) return multi_version_succeeded;
2835
2836 // Then we fetch the cover entry test
2837 ctrl = rce_cl->in(LoopNode::EntryControl);
2838 if (!ctrl->is_IfTrue() && !ctrl->is_IfFalse()) return multi_version_succeeded;
2839
2840#ifndef PRODUCT
2841 if (TraceLoopOpts) {
2842 tty->print("PostMultiVersion\n");
2843 rce_loop->dump_head();
2844 legacy_loop->dump_head();
2845 }
2846#endif
2847
2848 // Now fetch the limit we want to compare against
2849 Node *limit = rce_cl->limit();
2850 bool first_time = true;
2851
2852 // If we got this far, we identified the post loop which has been RCE'd and
2853 // we have a work list. Now we will try to transform the if guard to cause
2854 // the loop pair to be multi version executed with the determination left to runtime
2855 // or the optimizer if full information is known about the given arrays at compile time.
2856 Node *last_min = NULL;
2857 multi_version_succeeded = true;
2858 while (worklist.size()) {
2859 Node* rc_iffm = worklist.pop();
2860 if (rc_iffm->is_If()) {
2861 Node *rc_bolzm = rc_iffm->in(1);
2862 if (rc_bolzm->is_Bool()) {
2863 Node *rc_cmpzm = rc_bolzm->in(1);
2864 if (rc_cmpzm->is_Cmp()) {
2865 Node *rc_left = rc_cmpzm->in(2);
2866 if (rc_left->Opcode() != Op_LoadRange) {
2867 multi_version_succeeded = false;
2868 break;
2869 }
2870 if (first_time) {
2871 last_min = rc_left;
2872 first_time = false;
2873 } else {
2874 Node *cur_min = new MinINode(last_min, rc_left);
2875 last_min = cur_min;
2876 _igvn.register_new_node_with_optimizer(last_min);
2877 }
2878 }
2879 }
2880 }
2881 }
2882
2883 // All we have to do is update the limit of the rce loop
2884 // with the min of our expression and the current limit.
2885 // We will use this expression to replace the current limit.
2886 if (last_min && multi_version_succeeded) {
2887 Node *cur_min = new MinINode(last_min, limit);
2888 _igvn.register_new_node_with_optimizer(cur_min);
2889 Node *cmp_node = rce_loop_end->cmp_node();
2890 _igvn.replace_input_of(cmp_node, 2, cur_min);
2891 set_ctrl(cur_min, ctrl);
2892 set_loop(cur_min, rce_loop->_parent);
2893
2894 legacy_cl->mark_is_multiversioned();
2895 rce_cl->mark_is_multiversioned();
2896 multi_version_succeeded = true;
2897
2898 C->set_major_progress();
2899 }
2900
2901 return multi_version_succeeded;
2902}
2903
2904//-------------------------poison_rce_post_loop--------------------------------
2905// Causes the rce'd post loop to be optimized away if multiversioning fails
2906void PhaseIdealLoop::poison_rce_post_loop(IdealLoopTree *rce_loop) {
2907 CountedLoopNode *rce_cl = rce_loop->_head->as_CountedLoop();
2908 Node* ctrl = rce_cl->in(LoopNode::EntryControl);
2909 if (ctrl->is_IfTrue() || ctrl->is_IfFalse()) {
2910 Node* iffm = ctrl->in(0);
2911 if (iffm->is_If()) {
2912 Node* cur_bool = iffm->in(1);
2913 if (cur_bool->is_Bool()) {
2914 Node* cur_cmp = cur_bool->in(1);
2915 if (cur_cmp->is_Cmp()) {
2916 BoolTest::mask new_test = BoolTest::gt;
2917 BoolNode *new_bool = new BoolNode(cur_cmp, new_test);
2918 _igvn.replace_node(cur_bool, new_bool);
2919 _igvn._worklist.push(new_bool);
2920 Node* left_op = cur_cmp->in(1);
2921 _igvn.replace_input_of(cur_cmp, 2, left_op);
2922 C->set_major_progress();
2923 }
2924 }
2925 }
2926 }
2927}
2928
2929//------------------------------DCE_loop_body----------------------------------
2930// Remove simplistic dead code from loop body
2931void IdealLoopTree::DCE_loop_body() {
2932 for (uint i = 0; i < _body.size(); i++) {
2933 if (_body.at(i)->outcnt() == 0) {
2934 _body.map(i, _body.pop());
2935 i--; // Ensure we revisit the updated index.
2936 }
2937 }
2938}
2939
2940
2941//------------------------------adjust_loop_exit_prob--------------------------
2942// Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage.
2943// Replace with a 1-in-10 exit guess.
2944void IdealLoopTree::adjust_loop_exit_prob(PhaseIdealLoop *phase) {
2945 Node *test = tail();
2946 while (test != _head) {
2947 uint top = test->Opcode();
2948 if (top == Op_IfTrue || top == Op_IfFalse) {
2949 int test_con = ((ProjNode*)test)->_con;
2950 assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity");
2951 IfNode *iff = test->in(0)->as_If();
2952 if (iff->outcnt() == 2) { // Ignore dead tests
2953 Node *bol = iff->in(1);
2954 if (bol && bol->req() > 1 && bol->in(1) &&
2955 ((bol->in(1)->Opcode() == Op_StorePConditional) ||
2956 (bol->in(1)->Opcode() == Op_StoreIConditional) ||
2957 (bol->in(1)->Opcode() == Op_StoreLConditional) ||
2958 (bol->in(1)->Opcode() == Op_CompareAndExchangeB) ||
2959 (bol->in(1)->Opcode() == Op_CompareAndExchangeS) ||
2960 (bol->in(1)->Opcode() == Op_CompareAndExchangeI) ||
2961 (bol->in(1)->Opcode() == Op_CompareAndExchangeL) ||
2962 (bol->in(1)->Opcode() == Op_CompareAndExchangeP) ||
2963 (bol->in(1)->Opcode() == Op_CompareAndExchangeN) ||
2964 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapB) ||
2965 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapS) ||
2966 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapI) ||
2967 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapL) ||
2968 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapP) ||
2969 (bol->in(1)->Opcode() == Op_WeakCompareAndSwapN) ||
2970 (bol->in(1)->Opcode() == Op_CompareAndSwapB) ||
2971 (bol->in(1)->Opcode() == Op_CompareAndSwapS) ||
2972 (bol->in(1)->Opcode() == Op_CompareAndSwapI) ||
2973 (bol->in(1)->Opcode() == Op_CompareAndSwapL) ||
2974 (bol->in(1)->Opcode() == Op_CompareAndSwapP) ||
2975 (bol->in(1)->Opcode() == Op_CompareAndSwapN) ||
2976 (bol->in(1)->Opcode() == Op_ShenandoahCompareAndExchangeP) ||
2977 (bol->in(1)->Opcode() == Op_ShenandoahCompareAndExchangeN) ||
2978 (bol->in(1)->Opcode() == Op_ShenandoahWeakCompareAndSwapP) ||
2979 (bol->in(1)->Opcode() == Op_ShenandoahWeakCompareAndSwapN) ||
2980 (bol->in(1)->Opcode() == Op_ShenandoahCompareAndSwapP) ||
2981 (bol->in(1)->Opcode() == Op_ShenandoahCompareAndSwapN)))
2982 return; // Allocation loops RARELY take backedge
2983 // Find the OTHER exit path from the IF
2984 Node* ex = iff->proj_out(1-test_con);
2985 float p = iff->_prob;
2986 if (!phase->is_member(this, ex) && iff->_fcnt == COUNT_UNKNOWN) {
2987 if (top == Op_IfTrue) {
2988 if (p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) {
2989 iff->_prob = PROB_STATIC_FREQUENT;
2990 }
2991 } else {
2992 if (p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) {
2993 iff->_prob = PROB_STATIC_INFREQUENT;
2994 }
2995 }
2996 }
2997 }
2998 }
2999 test = phase->idom(test);
3000 }
3001}
3002
3003#ifdef ASSERT
3004static CountedLoopNode* locate_pre_from_main(CountedLoopNode *cl) {
3005 Node *ctrl = cl->skip_predicates();
3006 assert(ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "");
3007 Node *iffm = ctrl->in(0);
3008 assert(iffm->Opcode() == Op_If, "");
3009 Node *p_f = iffm->in(0);
3010 assert(p_f->Opcode() == Op_IfFalse, "");
3011 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
3012 assert(pre_end->loopnode()->is_pre_loop(), "");
3013 return pre_end->loopnode();
3014}
3015#endif
3016
3017// Remove the main and post loops and make the pre loop execute all
3018// iterations. Useful when the pre loop is found empty.
3019void IdealLoopTree::remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase) {
3020 CountedLoopEndNode* pre_end = cl->loopexit();
3021 Node* pre_cmp = pre_end->cmp_node();
3022 if (pre_cmp->in(2)->Opcode() != Op_Opaque1) {
3023 // Only safe to remove the main loop if the compiler optimized it
3024 // out based on an unknown number of iterations
3025 return;
3026 }
3027
3028 // Can we find the main loop?
3029 if (_next == NULL) {
3030 return;
3031 }
3032
3033 Node* next_head = _next->_head;
3034 if (!next_head->is_CountedLoop()) {
3035 return;
3036 }
3037
3038 CountedLoopNode* main_head = next_head->as_CountedLoop();
3039 if (!main_head->is_main_loop()) {
3040 return;
3041 }
3042
3043 assert(locate_pre_from_main(main_head) == cl, "bad main loop");
3044 Node* main_iff = main_head->skip_predicates()->in(0);
3045
3046 // Remove the Opaque1Node of the pre loop and make it execute all iterations
3047 phase->_igvn.replace_input_of(pre_cmp, 2, pre_cmp->in(2)->in(2));
3048 // Remove the Opaque1Node of the main loop so it can be optimized out
3049 Node* main_cmp = main_iff->in(1)->in(1);
3050 assert(main_cmp->in(2)->Opcode() == Op_Opaque1, "main loop has no opaque node?");
3051 phase->_igvn.replace_input_of(main_cmp, 2, main_cmp->in(2)->in(1));
3052}
3053
3054//------------------------------do_remove_empty_loop---------------------------
3055// We always attempt remove empty loops. The approach is to replace the trip
3056// counter with the value it will have on the last iteration. This will break
3057// the loop.
3058bool IdealLoopTree::do_remove_empty_loop(PhaseIdealLoop *phase) {
3059 // Minimum size must be empty loop
3060 if (_body.size() > EMPTY_LOOP_SIZE) {
3061 return false;
3062 }
3063 if (!_head->is_CountedLoop()) {
3064 return false; // Dead loop
3065 }
3066 CountedLoopNode *cl = _head->as_CountedLoop();
3067 if (!cl->is_valid_counted_loop()) {
3068 return false; // Malformed loop
3069 }
3070 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue)))) {
3071 return false; // Infinite loop
3072 }
3073 if (cl->is_pre_loop()) {
3074 // If the loop we are removing is a pre-loop then the main and post loop
3075 // can be removed as well.
3076 remove_main_post_loops(cl, phase);
3077 }
3078
3079#ifdef ASSERT
3080 // Ensure only one phi which is the iv.
3081 Node* iv = NULL;
3082 for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) {
3083 Node* n = cl->fast_out(i);
3084 if (n->Opcode() == Op_Phi) {
3085 assert(iv == NULL, "Too many phis");
3086 iv = n;
3087 }
3088 }
3089 assert(iv == cl->phi(), "Wrong phi");
3090#endif
3091
3092 // main and post loops have explicitly created zero trip guard
3093 bool needs_guard = !cl->is_main_loop() && !cl->is_post_loop();
3094 if (needs_guard) {
3095 // Skip guard if values not overlap.
3096 const TypeInt* init_t = phase->_igvn.type(cl->init_trip())->is_int();
3097 const TypeInt* limit_t = phase->_igvn.type(cl->limit())->is_int();
3098 int stride_con = cl->stride_con();
3099 if (stride_con > 0) {
3100 needs_guard = (init_t->_hi >= limit_t->_lo);
3101 } else {
3102 needs_guard = (init_t->_lo <= limit_t->_hi);
3103 }
3104 }
3105 if (needs_guard) {
3106 // Check for an obvious zero trip guard.
3107 Node* inctrl = PhaseIdealLoop::skip_all_loop_predicates(cl->skip_predicates());
3108 if (inctrl->Opcode() == Op_IfTrue || inctrl->Opcode() == Op_IfFalse) {
3109 bool maybe_swapped = (inctrl->Opcode() == Op_IfFalse);
3110 // The test should look like just the backedge of a CountedLoop
3111 Node* iff = inctrl->in(0);
3112 if (iff->is_If()) {
3113 Node* bol = iff->in(1);
3114 if (bol->is_Bool()) {
3115 BoolTest test = bol->as_Bool()->_test;
3116 if (maybe_swapped) {
3117 test._test = test.commute();
3118 test._test = test.negate();
3119 }
3120 if (test._test == cl->loopexit()->test_trip()) {
3121 Node* cmp = bol->in(1);
3122 int init_idx = maybe_swapped ? 2 : 1;
3123 int limit_idx = maybe_swapped ? 1 : 2;
3124 if (cmp->is_Cmp() && cmp->in(init_idx) == cl->init_trip() && cmp->in(limit_idx) == cl->limit()) {
3125 needs_guard = false;
3126 }
3127 }
3128 }
3129 }
3130 }
3131 }
3132
3133#ifndef PRODUCT
3134 if (PrintOpto) {
3135 tty->print("Removing empty loop with%s zero trip guard", needs_guard ? "out" : "");
3136 this->dump_head();
3137 } else if (TraceLoopOpts) {
3138 tty->print("Empty with%s zero trip guard ", needs_guard ? "out" : "");
3139 this->dump_head();
3140 }
3141#endif
3142
3143 if (needs_guard) {
3144 // Peel the loop to ensure there's a zero trip guard
3145 Node_List old_new;
3146 phase->do_peeling(this, old_new);
3147 }
3148
3149 // Replace the phi at loop head with the final value of the last
3150 // iteration. Then the CountedLoopEnd will collapse (backedge never
3151 // taken) and all loop-invariant uses of the exit values will be correct.
3152 Node *phi = cl->phi();
3153 Node *exact_limit = phase->exact_limit(this);
3154 if (exact_limit != cl->limit()) {
3155 // We also need to replace the original limit to collapse loop exit.
3156 Node* cmp = cl->loopexit()->cmp_node();
3157 assert(cl->limit() == cmp->in(2), "sanity");
3158 phase->_igvn._worklist.push(cmp->in(2)); // put limit on worklist
3159 phase->_igvn.replace_input_of(cmp, 2, exact_limit); // put cmp on worklist
3160 }
3161 // Note: the final value after increment should not overflow since
3162 // counted loop has limit check predicate.
3163 Node *final = new SubINode(exact_limit, cl->stride());
3164 phase->register_new_node(final,cl->in(LoopNode::EntryControl));
3165 phase->_igvn.replace_node(phi,final);
3166 phase->C->set_major_progress();
3167 return true;
3168}
3169
3170//------------------------------do_one_iteration_loop--------------------------
3171// Convert one iteration loop into normal code.
3172bool IdealLoopTree::do_one_iteration_loop(PhaseIdealLoop *phase) {
3173 if (!_head->as_Loop()->is_valid_counted_loop()) {
3174 return false; // Only for counted loop
3175 }
3176 CountedLoopNode *cl = _head->as_CountedLoop();
3177 if (!cl->has_exact_trip_count() || cl->trip_count() != 1) {
3178 return false;
3179 }
3180
3181#ifndef PRODUCT
3182 if (TraceLoopOpts) {
3183 tty->print("OneIteration ");
3184 this->dump_head();
3185 }
3186#endif
3187
3188 Node *init_n = cl->init_trip();
3189#ifdef ASSERT
3190 // Loop boundaries should be constant since trip count is exact.
3191 assert(init_n->get_int() + cl->stride_con() >= cl->limit()->get_int(), "should be one iteration");
3192#endif
3193 // Replace the phi at loop head with the value of the init_trip.
3194 // Then the CountedLoopEnd will collapse (backedge will not be taken)
3195 // and all loop-invariant uses of the exit values will be correct.
3196 phase->_igvn.replace_node(cl->phi(), cl->init_trip());
3197 phase->C->set_major_progress();
3198 return true;
3199}
3200
3201//=============================================================================
3202//------------------------------iteration_split_impl---------------------------
3203bool IdealLoopTree::iteration_split_impl(PhaseIdealLoop *phase, Node_List &old_new) {
3204 // Compute loop trip count if possible.
3205 compute_trip_count(phase);
3206
3207 // Convert one iteration loop into normal code.
3208 if (do_one_iteration_loop(phase)) {
3209 return true;
3210 }
3211 // Check and remove empty loops (spam micro-benchmarks)
3212 if (do_remove_empty_loop(phase)) {
3213 return true; // Here we removed an empty loop
3214 }
3215
3216 AutoNodeBudget node_budget(phase);
3217
3218 // Non-counted loops may be peeled; exactly 1 iteration is peeled.
3219 // This removes loop-invariant tests (usually null checks).
3220 if (!_head->is_CountedLoop()) { // Non-counted loop
3221 if (PartialPeelLoop && phase->partial_peel(this, old_new)) {
3222 // Partial peel succeeded so terminate this round of loop opts
3223 return false;
3224 }
3225 if (policy_peeling(phase)) { // Should we peel?
3226 if (PrintOpto) { tty->print_cr("should_peel"); }
3227 phase->do_peeling(this, old_new);
3228 } else if (policy_unswitching(phase)) {
3229 phase->do_unswitching(this, old_new);
3230 }
3231 return true;
3232 }
3233 CountedLoopNode *cl = _head->as_CountedLoop();
3234
3235 if (!cl->is_valid_counted_loop()) return true; // Ignore various kinds of broken loops
3236
3237 // Do nothing special to pre- and post- loops
3238 if (cl->is_pre_loop() || cl->is_post_loop()) return true;
3239
3240 // Compute loop trip count from profile data
3241 compute_profile_trip_cnt(phase);
3242
3243 // Before attempting fancy unrolling, RCE or alignment, see if we want
3244 // to completely unroll this loop or do loop unswitching.
3245 if (cl->is_normal_loop()) {
3246 if (policy_unswitching(phase)) {
3247 phase->do_unswitching(this, old_new);
3248 return true;
3249 }
3250 if (policy_maximally_unroll(phase)) {
3251 // Here we did some unrolling and peeling. Eventually we will
3252 // completely unroll this loop and it will no longer be a loop.
3253 phase->do_maximally_unroll(this, old_new);
3254 return true;
3255 }
3256 }
3257
3258 uint est_peeling = estimate_peeling(phase);
3259 bool should_peel = 0 < est_peeling;
3260
3261 // Counted loops may be peeled, may need some iterations run up
3262 // front for RCE, and may want to align loop refs to a cache
3263 // line. Thus we clone a full loop up front whose trip count is
3264 // at least 1 (if peeling), but may be several more.
3265
3266 // The main loop will start cache-line aligned with at least 1
3267 // iteration of the unrolled body (zero-trip test required) and
3268 // will have some range checks removed.
3269
3270 // A post-loop will finish any odd iterations (leftover after
3271 // unrolling), plus any needed for RCE purposes.
3272
3273 bool should_unroll = policy_unroll(phase);
3274 bool should_rce = policy_range_check(phase);
3275 // TODO: Remove align -- not used.
3276 bool should_align = policy_align(phase);
3277
3278 // If not RCE'ing (iteration splitting) or Aligning, then we do not need a
3279 // pre-loop. We may still need to peel an initial iteration but we will not
3280 // be needing an unknown number of pre-iterations.
3281 //
3282 // Basically, if may_rce_align reports FALSE first time through, we will not
3283 // be able to later do RCE or Aligning on this loop.
3284 bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align;
3285
3286 // If we have any of these conditions (RCE, alignment, unrolling) met, then
3287 // we switch to the pre-/main-/post-loop model. This model also covers
3288 // peeling.
3289 if (should_rce || should_align || should_unroll) {
3290 if (cl->is_normal_loop()) { // Convert to 'pre/main/post' loops
3291 uint estimate = est_loop_clone_sz(3);
3292 if (!phase->may_require_nodes(estimate)) {
3293 return false;
3294 }
3295 phase->insert_pre_post_loops(this, old_new, !may_rce_align);
3296 }
3297 // Adjust the pre- and main-loop limits to let the pre and post loops run
3298 // with full checks, but the main-loop with no checks. Remove said checks
3299 // from the main body.
3300 if (should_rce) {
3301 if (phase->do_range_check(this, old_new) != 0) {
3302 cl->mark_has_range_checks();
3303 }
3304 } else if (PostLoopMultiversioning) {
3305 phase->has_range_checks(this);
3306 }
3307
3308 if (should_unroll && !should_peel && PostLoopMultiversioning) {
3309 // Try to setup multiversioning on main loops before they are unrolled
3310 if (cl->is_main_loop() && (cl->unrolled_count() == 1)) {
3311 phase->insert_scalar_rced_post_loop(this, old_new);
3312 }
3313 }
3314
3315 // Double loop body for unrolling. Adjust the minimum-trip test (will do
3316 // twice as many iterations as before) and the main body limit (only do
3317 // an even number of trips). If we are peeling, we might enable some RCE
3318 // and we'd rather unroll the post-RCE'd loop SO... do not unroll if
3319 // peeling.
3320 if (should_unroll && !should_peel) {
3321 if (SuperWordLoopUnrollAnalysis) {
3322 phase->insert_vector_post_loop(this, old_new);
3323 }
3324 phase->do_unroll(this, old_new, true);
3325 }
3326
3327 // Adjust the pre-loop limits to align the main body iterations.
3328 if (should_align) {
3329 Unimplemented();
3330 }
3331 } else { // Else we have an unchanged counted loop
3332 if (should_peel) { // Might want to peel but do nothing else
3333 if (phase->may_require_nodes(est_peeling)) {
3334 phase->do_peeling(this, old_new);
3335 }
3336 }
3337 }
3338 return true;
3339}
3340
3341
3342//=============================================================================
3343//------------------------------iteration_split--------------------------------
3344bool IdealLoopTree::iteration_split(PhaseIdealLoop* phase, Node_List &old_new) {
3345 // Recursively iteration split nested loops
3346 if (_child && !_child->iteration_split(phase, old_new)) {
3347 return false;
3348 }
3349
3350 // Clean out prior deadwood
3351 DCE_loop_body();
3352
3353 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
3354 // Replace with a 1-in-10 exit guess.
3355 if (!is_root() && is_loop()) {
3356 adjust_loop_exit_prob(phase);
3357 }
3358
3359 // Unrolling, RCE and peeling efforts, iff innermost loop.
3360 if (_allow_optimizations && is_innermost()) {
3361 if (!_has_call) {
3362 if (!iteration_split_impl(phase, old_new)) {
3363 return false;
3364 }
3365 } else {
3366 AutoNodeBudget node_budget(phase);
3367 if (policy_unswitching(phase)) {
3368 phase->do_unswitching(this, old_new);
3369 }
3370 }
3371 }
3372
3373 // Minor offset re-organization to remove loop-fallout uses of
3374 // trip counter when there was no major reshaping.
3375 phase->reorg_offsets(this);
3376
3377 if (_next && !_next->iteration_split(phase, old_new)) {
3378 return false;
3379 }
3380 return true;
3381}
3382
3383
3384//=============================================================================
3385// Process all the loops in the loop tree and replace any fill
3386// patterns with an intrinsic version.
3387bool PhaseIdealLoop::do_intrinsify_fill() {
3388 bool changed = false;
3389 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
3390 IdealLoopTree* lpt = iter.current();
3391 changed |= intrinsify_fill(lpt);
3392 }
3393 return changed;
3394}
3395
3396
3397// Examine an inner loop looking for a a single store of an invariant
3398// value in a unit stride loop,
3399bool PhaseIdealLoop::match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
3400 Node*& shift, Node*& con) {
3401 const char* msg = NULL;
3402 Node* msg_node = NULL;
3403
3404 store_value = NULL;
3405 con = NULL;
3406 shift = NULL;
3407
3408 // Process the loop looking for stores. If there are multiple
3409 // stores or extra control flow give at this point.
3410 CountedLoopNode* head = lpt->_head->as_CountedLoop();
3411 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3412 Node* n = lpt->_body.at(i);
3413 if (n->outcnt() == 0) continue; // Ignore dead
3414 if (n->is_Store()) {
3415 if (store != NULL) {
3416 msg = "multiple stores";
3417 break;
3418 }
3419 int opc = n->Opcode();
3420 if (opc == Op_StoreP || opc == Op_StoreN || opc == Op_StoreNKlass || opc == Op_StoreCM) {
3421 msg = "oop fills not handled";
3422 break;
3423 }
3424 Node* value = n->in(MemNode::ValueIn);
3425 if (!lpt->is_invariant(value)) {
3426 msg = "variant store value";
3427 } else if (!_igvn.type(n->in(MemNode::Address))->isa_aryptr()) {
3428 msg = "not array address";
3429 }
3430 store = n;
3431 store_value = value;
3432 } else if (n->is_If() && n != head->loopexit_or_null()) {
3433 msg = "extra control flow";
3434 msg_node = n;
3435 }
3436 }
3437
3438 if (store == NULL) {
3439 // No store in loop
3440 return false;
3441 }
3442
3443 if (msg == NULL && head->stride_con() != 1) {
3444 // could handle negative strides too
3445 if (head->stride_con() < 0) {
3446 msg = "negative stride";
3447 } else {
3448 msg = "non-unit stride";
3449 }
3450 }
3451
3452 if (msg == NULL && !store->in(MemNode::Address)->is_AddP()) {
3453 msg = "can't handle store address";
3454 msg_node = store->in(MemNode::Address);
3455 }
3456
3457 if (msg == NULL &&
3458 (!store->in(MemNode::Memory)->is_Phi() ||
3459 store->in(MemNode::Memory)->in(LoopNode::LoopBackControl) != store)) {
3460 msg = "store memory isn't proper phi";
3461 msg_node = store->in(MemNode::Memory);
3462 }
3463
3464 // Make sure there is an appropriate fill routine
3465 BasicType t = store->as_Mem()->memory_type();
3466 const char* fill_name;
3467 if (msg == NULL &&
3468 StubRoutines::select_fill_function(t, false, fill_name) == NULL) {
3469 msg = "unsupported store";
3470 msg_node = store;
3471 }
3472
3473 if (msg != NULL) {
3474#ifndef PRODUCT
3475 if (TraceOptimizeFill) {
3476 tty->print_cr("not fill intrinsic candidate: %s", msg);
3477 if (msg_node != NULL) msg_node->dump();
3478 }
3479#endif
3480 return false;
3481 }
3482
3483 // Make sure the address expression can be handled. It should be
3484 // head->phi * elsize + con. head->phi might have a ConvI2L(CastII()).
3485 Node* elements[4];
3486 Node* cast = NULL;
3487 Node* conv = NULL;
3488 bool found_index = false;
3489 int count = store->in(MemNode::Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
3490 for (int e = 0; e < count; e++) {
3491 Node* n = elements[e];
3492 if (n->is_Con() && con == NULL) {
3493 con = n;
3494 } else if (n->Opcode() == Op_LShiftX && shift == NULL) {
3495 Node* value = n->in(1);
3496#ifdef _LP64
3497 if (value->Opcode() == Op_ConvI2L) {
3498 conv = value;
3499 value = value->in(1);
3500 }
3501 if (value->Opcode() == Op_CastII &&
3502 value->as_CastII()->has_range_check()) {
3503 // Skip range check dependent CastII nodes
3504 cast = value;
3505 value = value->in(1);
3506 }
3507#endif
3508 if (value != head->phi()) {
3509 msg = "unhandled shift in address";
3510 } else {
3511 if (type2aelembytes(store->as_Mem()->memory_type(), true) != (1 << n->in(2)->get_int())) {
3512 msg = "scale doesn't match";
3513 } else {
3514 found_index = true;
3515 shift = n;
3516 }
3517 }
3518 } else if (n->Opcode() == Op_ConvI2L && conv == NULL) {
3519 conv = n;
3520 n = n->in(1);
3521 if (n->Opcode() == Op_CastII &&
3522 n->as_CastII()->has_range_check()) {
3523 // Skip range check dependent CastII nodes
3524 cast = n;
3525 n = n->in(1);
3526 }
3527 if (n == head->phi()) {
3528 found_index = true;
3529 } else {
3530 msg = "unhandled input to ConvI2L";
3531 }
3532 } else if (n == head->phi()) {
3533 // no shift, check below for allowed cases
3534 found_index = true;
3535 } else {
3536 msg = "unhandled node in address";
3537 msg_node = n;
3538 }
3539 }
3540
3541 if (count == -1) {
3542 msg = "malformed address expression";
3543 msg_node = store;
3544 }
3545
3546 if (!found_index) {
3547 msg = "missing use of index";
3548 }
3549
3550 // byte sized items won't have a shift
3551 if (msg == NULL && shift == NULL && t != T_BYTE && t != T_BOOLEAN) {
3552 msg = "can't find shift";
3553 msg_node = store;
3554 }
3555
3556 if (msg != NULL) {
3557#ifndef PRODUCT
3558 if (TraceOptimizeFill) {
3559 tty->print_cr("not fill intrinsic: %s", msg);
3560 if (msg_node != NULL) msg_node->dump();
3561 }
3562#endif
3563 return false;
3564 }
3565
3566 // No make sure all the other nodes in the loop can be handled
3567 VectorSet ok(Thread::current()->resource_area());
3568
3569 // store related values are ok
3570 ok.set(store->_idx);
3571 ok.set(store->in(MemNode::Memory)->_idx);
3572
3573 CountedLoopEndNode* loop_exit = head->loopexit();
3574
3575 // Loop structure is ok
3576 ok.set(head->_idx);
3577 ok.set(loop_exit->_idx);
3578 ok.set(head->phi()->_idx);
3579 ok.set(head->incr()->_idx);
3580 ok.set(loop_exit->cmp_node()->_idx);
3581 ok.set(loop_exit->in(1)->_idx);
3582
3583 // Address elements are ok
3584 if (con) ok.set(con->_idx);
3585 if (shift) ok.set(shift->_idx);
3586 if (cast) ok.set(cast->_idx);
3587 if (conv) ok.set(conv->_idx);
3588
3589 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3590 Node* n = lpt->_body.at(i);
3591 if (n->outcnt() == 0) continue; // Ignore dead
3592 if (ok.test(n->_idx)) continue;
3593 // Backedge projection is ok
3594 if (n->is_IfTrue() && n->in(0) == loop_exit) continue;
3595 if (!n->is_AddP()) {
3596 msg = "unhandled node";
3597 msg_node = n;
3598 break;
3599 }
3600 }
3601
3602 // Make sure no unexpected values are used outside the loop
3603 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
3604 Node* n = lpt->_body.at(i);
3605 // These values can be replaced with other nodes if they are used
3606 // outside the loop.
3607 if (n == store || n == loop_exit || n == head->incr() || n == store->in(MemNode::Memory)) continue;
3608 for (SimpleDUIterator iter(n); iter.has_next(); iter.next()) {
3609 Node* use = iter.get();
3610 if (!lpt->_body.contains(use)) {
3611 msg = "node is used outside loop";
3612 // lpt->_body.dump();
3613 msg_node = n;
3614 break;
3615 }
3616 }
3617 }
3618
3619#ifdef ASSERT
3620 if (TraceOptimizeFill) {
3621 if (msg != NULL) {
3622 tty->print_cr("no fill intrinsic: %s", msg);
3623 if (msg_node != NULL) msg_node->dump();
3624 } else {
3625 tty->print_cr("fill intrinsic for:");
3626 }
3627 store->dump();
3628 if (Verbose) {
3629 lpt->_body.dump();
3630 }
3631 }
3632#endif
3633
3634 return msg == NULL;
3635}
3636
3637
3638
3639bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) {
3640 // Only for counted inner loops
3641 if (!lpt->is_counted() || !lpt->is_innermost()) {
3642 return false;
3643 }
3644
3645 // Must have constant stride
3646 CountedLoopNode* head = lpt->_head->as_CountedLoop();
3647 if (!head->is_valid_counted_loop() || !head->is_normal_loop()) {
3648 return false;
3649 }
3650
3651 head->verify_strip_mined(1);
3652
3653 // Check that the body only contains a store of a loop invariant
3654 // value that is indexed by the loop phi.
3655 Node* store = NULL;
3656 Node* store_value = NULL;
3657 Node* shift = NULL;
3658 Node* offset = NULL;
3659 if (!match_fill_loop(lpt, store, store_value, shift, offset)) {
3660 return false;
3661 }
3662
3663 Node* exit = head->loopexit()->proj_out_or_null(0);
3664 if (exit == NULL) {
3665 return false;
3666 }
3667
3668#ifndef PRODUCT
3669 if (TraceLoopOpts) {
3670 tty->print("ArrayFill ");
3671 lpt->dump_head();
3672 }
3673#endif
3674
3675 // Now replace the whole loop body by a call to a fill routine that
3676 // covers the same region as the loop.
3677 Node* base = store->in(MemNode::Address)->as_AddP()->in(AddPNode::Base);
3678
3679 // Build an expression for the beginning of the copy region
3680 Node* index = head->init_trip();
3681#ifdef _LP64
3682 index = new ConvI2LNode(index);
3683 _igvn.register_new_node_with_optimizer(index);
3684#endif
3685 if (shift != NULL) {
3686 // byte arrays don't require a shift but others do.
3687 index = new LShiftXNode(index, shift->in(2));
3688 _igvn.register_new_node_with_optimizer(index);
3689 }
3690 index = new AddPNode(base, base, index);
3691 _igvn.register_new_node_with_optimizer(index);
3692 Node* from = new AddPNode(base, index, offset);
3693 _igvn.register_new_node_with_optimizer(from);
3694 // Compute the number of elements to copy
3695 Node* len = new SubINode(head->limit(), head->init_trip());
3696 _igvn.register_new_node_with_optimizer(len);
3697
3698 BasicType t = store->as_Mem()->memory_type();
3699 bool aligned = false;
3700 if (offset != NULL && head->init_trip()->is_Con()) {
3701 int element_size = type2aelembytes(t);
3702 aligned = (offset->find_intptr_t_type()->get_con() + head->init_trip()->get_int() * element_size) % HeapWordSize == 0;
3703 }
3704
3705 // Build a call to the fill routine
3706 const char* fill_name;
3707 address fill = StubRoutines::select_fill_function(t, aligned, fill_name);
3708 assert(fill != NULL, "what?");
3709
3710 // Convert float/double to int/long for fill routines
3711 if (t == T_FLOAT) {
3712 store_value = new MoveF2INode(store_value);
3713 _igvn.register_new_node_with_optimizer(store_value);
3714 } else if (t == T_DOUBLE) {
3715 store_value = new MoveD2LNode(store_value);
3716 _igvn.register_new_node_with_optimizer(store_value);
3717 }
3718
3719 Node* mem_phi = store->in(MemNode::Memory);
3720 Node* result_ctrl;
3721 Node* result_mem;
3722 const TypeFunc* call_type = OptoRuntime::array_fill_Type();
3723 CallLeafNode *call = new CallLeafNoFPNode(call_type, fill,
3724 fill_name, TypeAryPtr::get_array_body_type(t));
3725 uint cnt = 0;
3726 call->init_req(TypeFunc::Parms + cnt++, from);
3727 call->init_req(TypeFunc::Parms + cnt++, store_value);
3728#ifdef _LP64
3729 len = new ConvI2LNode(len);
3730 _igvn.register_new_node_with_optimizer(len);
3731#endif
3732 call->init_req(TypeFunc::Parms + cnt++, len);
3733#ifdef _LP64
3734 call->init_req(TypeFunc::Parms + cnt++, C->top());
3735#endif
3736 call->init_req(TypeFunc::Control, head->init_control());
3737 call->init_req(TypeFunc::I_O, C->top()); // Does no I/O.
3738 call->init_req(TypeFunc::Memory, mem_phi->in(LoopNode::EntryControl));
3739 call->init_req(TypeFunc::ReturnAdr, C->start()->proj_out_or_null(TypeFunc::ReturnAdr));
3740 call->init_req(TypeFunc::FramePtr, C->start()->proj_out_or_null(TypeFunc::FramePtr));
3741 _igvn.register_new_node_with_optimizer(call);
3742 result_ctrl = new ProjNode(call,TypeFunc::Control);
3743 _igvn.register_new_node_with_optimizer(result_ctrl);
3744 result_mem = new ProjNode(call,TypeFunc::Memory);
3745 _igvn.register_new_node_with_optimizer(result_mem);
3746
3747/* Disable following optimization until proper fix (add missing checks).
3748
3749 // If this fill is tightly coupled to an allocation and overwrites
3750 // the whole body, allow it to take over the zeroing.
3751 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, this);
3752 if (alloc != NULL && alloc->is_AllocateArray()) {
3753 Node* length = alloc->as_AllocateArray()->Ideal_length();
3754 if (head->limit() == length &&
3755 head->init_trip() == _igvn.intcon(0)) {
3756 if (TraceOptimizeFill) {
3757 tty->print_cr("Eliminated zeroing in allocation");
3758 }
3759 alloc->maybe_set_complete(&_igvn);
3760 } else {
3761#ifdef ASSERT
3762 if (TraceOptimizeFill) {
3763 tty->print_cr("filling array but bounds don't match");
3764 alloc->dump();
3765 head->init_trip()->dump();
3766 head->limit()->dump();
3767 length->dump();
3768 }
3769#endif
3770 }
3771 }
3772*/
3773
3774 if (head->is_strip_mined()) {
3775 // Inner strip mined loop goes away so get rid of outer strip
3776 // mined loop
3777 Node* outer_sfpt = head->outer_safepoint();
3778 Node* in = outer_sfpt->in(0);
3779 Node* outer_out = head->outer_loop_exit();
3780 lazy_replace(outer_out, in);
3781 _igvn.replace_input_of(outer_sfpt, 0, C->top());
3782 }
3783
3784 // Redirect the old control and memory edges that are outside the loop.
3785 // Sometimes the memory phi of the head is used as the outgoing
3786 // state of the loop. It's safe in this case to replace it with the
3787 // result_mem.
3788 _igvn.replace_node(store->in(MemNode::Memory), result_mem);
3789 lazy_replace(exit, result_ctrl);
3790 _igvn.replace_node(store, result_mem);
3791 // Any uses the increment outside of the loop become the loop limit.
3792 _igvn.replace_node(head->incr(), head->limit());
3793
3794 // Disconnect the head from the loop.
3795 for (uint i = 0; i < lpt->_body.size(); i++) {
3796 Node* n = lpt->_body.at(i);
3797 _igvn.replace_node(n, C->top());
3798 }
3799
3800 return true;
3801}
3802